Time perception

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Time_perception 

The study of time perception or chronoception is a field within psychology, cognitive linguistics and neuroscience that refers to the subjective experience, or sense, of time, which is measured by someone's own perception of the duration of the indefinite and unfolding of events. The perceived time interval between two successive events is referred to as perceived duration. Though directly experiencing or understanding another person's perception of time is not possible, perception can be objectively studied and inferred through a number of scientific experiments. Some temporal illusions help to expose the underlying neural mechanisms of time perception.

The ancient Greeks recognized the difference between chronological time (chronos) and subjective time (Kairos).

Pioneering work on time perception, emphasizing species-specific differences, was conducted by Karl Ernst von Baer.

Theories

Time perception is typically categorized in three distinct ranges, because different ranges of duration are processed in different areas of the brain:

• Sub-second timing or millisecond timing
• Interval timing or seconds-to-minutes timing
• Circadian timing

There are many theories and computational models for time perception mechanisms in the brain. William J. Friedman (1993) contrasted two theories of the sense of time:

• The strength model of time memory. This posits a memory trace that persists over time, by which one might judge the age of a memory (and therefore how long ago the event remembered occurred) from the strength of the trace. This conflicts with the fact that memories of recent events may fade more quickly than more distant memories.
• The inference model suggests the time of an event is inferred from information about relations between the event in question and other events whose date or time is known.

Another hypothesis involves the brain's subconscious tallying of "pulses" during a specific interval, forming a biological stopwatch. This theory proposes that the brain can run multiple biological stopwatches independently depending on the type of tasks being tracked. The source and nature of the pulses is unclear. They are as yet a metaphor whose correspondence to brain anatomy or physiology is unknown.

Philosophical perspectives

Main article: Specious present

The specious present is the time duration wherein a state of consciousness is experienced as being in the present. The term was first introduced by the philosopher E. R. Clay in 1882 (E. Robert Kelly), and was further developed by William James. James defined the specious present to be "the prototype of all conceived times... the short duration of which we are immediately and incessantly sensible". In "Scientific Thought" (1930), C. D. Broad further elaborated on the concept of the specious present and considered that the specious present may be considered as the temporal equivalent of a sensory datum. A version of the concept was used by Edmund Husserl in his works and discussed further by Francisco Varela based on the writings of Husserl, Heidegger, and Merleau-Ponty.

Although the perception of time is not associated with a specific sensory system, psychologists and neuroscientists suggest that humans do have a system, or several complementary systems, governing the perception of time. Time perception is handled by a highly distributed system involving the cerebral cortex, cerebellum and basal ganglia. One particular component, the suprachiasmatic nucleus, is responsible for the circadian (or daily) rhythm, while other cell clusters appear to be capable of shorter (ultradian) timekeeping. There is some evidence that very short (millisecond) durations are processed by dedicated neurons in early sensory parts of the brain.

Warren Meck devised a physiological model for measuring the passage of time. He found the representation of time to be generated by the oscillatory activity of cells in the upper cortex. The frequency of these cells' activity is detected by cells in the dorsal striatum at the base of the forebrain. His model separated explicit timing and implicit timing. Explicit timing is used in estimating the duration of a stimulus. Implicit timing is used to gauge the amount of time separating one from an impending event that is expected to occur in the near future. These two estimations of time do not involve the same neuroanatomical areas. For example, implicit timing often occurs to achieve a motor task, involving the cerebellum, left parietal cortex, and left premotor cortex. Explicit timing often involves the supplementary motor area and the right prefrontal cortex.

Two visual stimuli, inside someone's field of view, can be successfully regarded as simultaneous up to five milliseconds.

In the popular essay "Brain Time", David Eagleman explains that different types of sensory information (auditory, tactile, visual, etc.) are processed at different speeds by different neural architectures. The brain must learn how to overcome these speed disparities if it is to create a temporally unified representation of the external world:

if the visual brain wants to get events correct timewise, it may have only one choice: wait for the slowest information to arrive. To accomplish this, it must wait about a tenth of a second. In the early days of television broadcasting, engineers worried about the problem of keeping audio and video signals synchronized. Then they accidentally discovered that they had around a hundred milliseconds of slop: As long as the signals arrived within this window, viewers' brains would automatically resynchronize the signals. He goes on to say, "This brief waiting period allows the visual system to discount the various delays imposed by the early stages; however, it has the disadvantage of pushing perception into the past. There is a distinct survival advantage to operating as close to the present as possible; an animal does not want to live too far in the past. Therefore, the tenth-of-a-second window may be the smallest delay that allows higher areas of the brain to account for the delays created in the first stages of the system while still operating near the border of the present. This window of delay means that awareness is retroactive, incorporating data from a window of time after an event and delivering a delayed interpretation of what happened."

Experiments have shown that rats can successfully estimate a time interval of approximately 40 seconds, despite having their cortex entirely removed. This suggests that time estimation may be a low level process.

Ecological perspectives

In recent history, ecologists and psychologists have been interested in whether and how time is perceived by non-human animals, as well as which functional purposes are served by the ability to perceive time. Studies have demonstrated that many species of animals, including both vertebrates and invertebrates, have cognitive abilities that allow them to estimate and compare time intervals and durations in a similar way to humans.

There is empirical evidence that metabolic rate has an impact on animals' ability to perceive time. In general, it is true within and across taxa that animals of smaller size (such as flies), which have a fast metabolic rate, experience time more slowly than animals of larger size, which have a slow metabolic rate. Researchers suppose that this could be the reason why small-bodied animals are generally better at perceiving time on a small scale, and why they are more agile than larger animals.

Time perception in vertebrates

Examples in fish

In a lab experiment, goldfish were conditioned to receive a light stimulus followed shortly by an aversive electric shock, with a constant time interval between the two stimuli. Test subjects showed an increase in general activity around the time of the electric shock. This response persisted in further trials in which the light stimulus was kept but the electric shock was removed. This suggests that goldfish are able to perceive time intervals and to initiate an avoidance response at the time when they expect the distressing stimulus to happen.

In two separate studies, golden shiners and dwarf inangas demonstrated the ability to associate the availability of food sources to specific locations and times of day, called time-place learning. In contrast, when tested for time-place learning based on predation risk, inangas were unable to associate spatiotemporal patterns to the presence or absence of predators.

In June 2022, researchers reported in Physical Review Letters finding that salamanders were demonstrating counter-intuitive responses to the arrow of time in how their eyes perceived different stimuli.

Examples in birds

When presented with the choice between obtaining food at regular intervals (with a fixed delay between feedings) or at stochastic intervals (with a variable delay between feedings), starlings can discriminate between the two types of intervals and consistently prefer getting food at variable intervals. This is true whether the total amount of food is the same for both options or if the total amount of food is unpredictable in the variable option. This suggests that starlings have an inclination for risk-prone behavior.

Pigeons are able to discriminate between different times of day and show time-place learning. After training, lab subjects were successfully able to peck specific keys at different times of day (morning or afternoon) in exchange for food, even after their sleep/wake cycle was artificially shifted. This suggests that to discriminate between different times of day, pigeons can use an internal timer (or circadian timer) that is independent of external cues. However, a more recent study on time-place learning in pigeons suggests that for a similar task, test subjects will switch to a non-circadian timing mechanism when possible to save energy resources. Experimental tests revealed that pigeons are also able to discriminate between cues of various durations (on the order of seconds), but that they are less accurate when timing auditory cues than when timing visual cues.

Examples in mammals

A study on privately owned dogs revealed that dogs are able to perceive durations ranging from minutes to several hours differently. Dogs reacted with increasing intensity to the return of their owners when they were left alone for longer durations, regardless of the owners' behavior.

After being trained with food reinforcement, female wild boars are able to correctly estimate time intervals of days by asking for food at the end of each interval, but they are unable to accurately estimate time intervals of minutes with the same training method.

When trained with positive reinforcement, rats can learn to respond to a signal of a certain duration, but not to signals of shorter or longer durations, which demonstrates that they can discriminate between different durations. Rats have demonstrated time-place learning, and can also learn to infer correct timing for a specific task by following an order of events, suggesting that they might be able to use an ordinal timing mechanism. Like pigeons, rats are thought to have the ability to use a circadian timing mechanism for discriminating time of day.

Time perception in invertebrates

Forager honey bee flying back to the hive with pollen and nectar

When returning to the hive with nectar, forager honey bees need to know the current ratio of nectar-collecting to nectar-processing rates in the colony. To do so, they estimate the time it takes them to find a food-storer bee, which will unload the forage and store it. The longer it takes them to find one, the busier the food-storer bees are; and therefore the higher the nectar-collecting rate of the colony. Forager bees also assess the quality of nectar by comparing the length of time it takes to unload the forage: a longer unloading time indicates higher quality nectar. They compare their own unloading time to the unloading time of other foragers present in the hive, and adjust their recruiting behavior accordingly. For instance, honey bees reduce the duration of their waggle dance if they judge their own yield to be inferior. Scientists have demonstrated that anesthesia disrupts the circadian clock and impairs the time perception of honey bees, as observed in humans. Experiments revealed that a 6-hour-long general anesthesia significantly delayed the start of the foraging behaviour of honeybees if induced during daytime, but not if induced during nighttime.

Bumble bees can be successfully trained to respond to a stimulus after a certain time interval has elapsed (usually several seconds after the start signal). Studies have shown that they can also learn to simultaneously time multiple interval durations.

In a single study, colonies from three species of ants from the genus Myrmica were trained to associate feeding sessions with different times. The trainings lasted several days, where each day the feeding time was delayed by 20 minutes compared to the previous day. In all three species, at the end of the training, most individuals were present at the feeding spot at the correct expected times, suggesting that ants are able to estimate the time running, keep in memory the expected feeding time and to act anticipatively.

Types of temporal illusions

A temporal illusion is a distortion in the perception of time. For example:

• estimating time intervals, e.g., "When did you last see your primary care physician?";
• estimating time duration, e.g., "How long were you waiting at the doctor's office?"; and
• judging the simultaneity of events (see below for examples).

Main types of temporal illusions

• Telescoping effect: People tend to recall recent events as occurring further back in time than they actually did (backward telescoping) and distant events as occurring more recently than they actually did (forward telescoping).
• Vierordt's law: Shorter intervals tend to be overestimated while longer intervals tend to be underestimated
• Time intervals associated with more changes may be perceived as longer than intervals with fewer changes
• Perceived temporal length of a given task may shorten with greater motivation
• Perceived temporal length of a given task may stretch when broken up or interrupted
• Auditory stimuli may appear to last longer than visual stimuli
• Time durations may appear longer with greater stimulus intensity (e.g., auditory loudness or pitch)
• Simultaneity judgments can be manipulated by repeated exposure to non-simultaneous stimuli

Kappa effect

The Kappa effect or perceptual time dilation is a form of temporal illusion verifiable by experiment.^[57] The temporal duration between a sequence of consecutive stimuli is thought to be relatively longer or shorter than its actual elapsed time, due to the spatial/auditory/tactile separation between each consecutive stimuli. The kappa effect can be displayed when considering a journey made in two parts that each take an equal amount of time. When mentally comparing these two sub-journeys, the part that covers more distance may appear to take longer than the part covering less distance, even though they take an equal amount of time.

Eye movements and "Chronostasis"

The perception of space and time undergoes distortions during rapid saccadic eye movements. Chronostasis is a type of temporal illusion in which the first impression following the introduction of a new event or task demand to the brain appears to be extended in time. For example, chronostasis temporarily occurs when fixating on a target stimulus, immediately following a saccade (e.g., quick eye movement). This elicits an overestimation in the temporal duration for which that target stimulus (i.e., postsaccadic stimulus) was perceived. This effect can extend apparent durations by up to 500 ms and is consistent with the idea that the visual system models events prior to perception. The most well-known version of this illusion is known as the stopped-clock illusion, wherein a subject's first impression of the second-hand movement of an analog clock, subsequent to one's directed attention (i.e., saccade) to the clock, is the perception of a slower-than-normal second-hand movement rate (the seconds hand of the clock may seemingly temporarily freeze in place after initially looking at it).

The occurrence of chronostasis extends beyond the visual domain into the auditory and tactile domains. In the auditory domain, chronostasis and duration overestimation occur when observing auditory stimuli. One common example is a frequent occurrence when making telephone calls. If, while listening to the phone's dial tone, research subjects move the phone from one ear to the other, the length of time between rings appears longer. In the tactile domain, chronostasis has persisted in research subjects as they reach for and grasp objects. After grasping a new object, subjects overestimate the time in which their hand has been in contact with this object.

Flash-lag effect

Main article: Flash lag illusion

In an experiment, participants were told to stare at an "x" symbol on a computer screen whereby a moving blue doughnut-like ring repeatedly circled the fixed "x" point. Occasionally, the ring would display a white flash for a split second that physically overlapped the ring's interior. However, when asked what was perceived, participants responded that they saw the white flash lagging behind the center of the moving ring. In other words, despite the reality that the two retinal images were actually spatially aligned, the flashed object was usually observed to trail a continuously moving object in space — a phenomenon referred to as the flash-lag effect.

The first proposed explanation, called the "motion extrapolation" hypothesis, is that the visual system extrapolates the position of moving objects but not flashing objects when accounting for neural delays (i.e., the lag time between the retinal image and the observer's perception of the flashing object). The second proposed explanation by David Eagleman and Sejnowski, called the "latency difference" hypothesis, is that the visual system processes moving objects at a faster rate than flashed objects. In the attempt to disprove the first hypothesis, David Eagleman conducted an experiment in which the moving ring suddenly reverses direction to spin in the other way as the flashed object briefly appears. If the first hypothesis were correct, we would expect that, immediately following reversal, the moving object would be observed as lagging behind the flashed object. However, the experiment revealed the opposite — immediately following reversal, the flashed object was observed as lagging behind the moving object. This experimental result supports the "latency difference" hypothesis. A recent study tries to reconcile these different approaches by treating perception as an inference mechanism aiming at describing what is happening at the present time.

Oddball effect

Humans typically overestimate the perceived duration of the initial and final event in a stream of identical events. This oddball effect may serve an evolutionarily adapted "alerting" function and is consistent with reports of time slowing down in threatening situations. The effect seems to be strongest for images that are expanding in size on the retina, in other words, that are "looming" or approaching the viewer, and the effect can be eradicated for oddballs that are contracting or perceived to be receding from the viewer. The effect is also reduced or reversed with a static oddball presented among a stream of expanding stimuli.

Initial studies suggested that this oddball-induced "subjective time dilation" expanded the perceived duration of oddball stimuli by 30–50% but subsequent research has reported more modest expansion of around 10% or less. The direction of the effect, whether the viewer perceives an increase or a decrease in duration, also seems to be dependent upon the stimulus used.

Reversal of temporal order judgment

Numerous experimental findings suggest that temporal order judgments of actions preceding effects can be reversed under special circumstances. Experiments have shown that sensory simultaneity judgments can be manipulated by repeated exposure to non-simultaneous stimuli. In an experiment conducted by David Eagleman, a temporal order judgment reversal was induced in subjects by exposing them to delayed motor consequences. In the experiment, subjects played various forms of video games. Unknown to the subjects, the experimenters introduced a fixed delay between the mouse movements and the subsequent sensory feedback. For example, a subject may not see a movement register on the screen until 150 milliseconds after they had moved the mouse. Participants playing the game quickly adapted to the delay and felt as though there was less delay between their mouse movement and the sensory feedback. Shortly after the experimenters removed the delay, the subjects commonly felt as though the effect on the screen happened just before they commanded it. This work addresses how the perceived timing of effects is modulated by expectations, and the extent to which such predictions are quickly modifiable.

In an experiment conducted by Haggard and colleagues in 2002, participants pressed a button that triggered a flash of light at a distance, after a slight delay of 100 milliseconds. By repeatedly engaging in this act, participants had adapted to the delay (i.e., they experienced a gradual shortening in the perceived time interval between pressing the button and seeing the flash of light). The experimenters then showed the flash of light instantly after the button was pressed. In response, subjects often thought that the flash (the effect) had occurred before the button was pressed (the cause). Additionally, when the experimenters slightly reduced the delay, and shortened the spatial distance between the button and the flash of light, participants had often claimed again to have experienced the effect before the cause.

Several experiments also suggest that temporal order judgment of a pair of tactile stimuli delivered in rapid succession, one to each hand, is noticeably impaired (i.e., misreported) by crossing the hands over the midline. However, congenitally blind subjects showed no trace of temporal order judgment reversal after crossing the arms. These results suggest that tactile signals taken in by the congenitally blind are ordered in time without being referred to a visuospatial representation. Unlike the congenitally blind subjects, the temporal order judgments of the late-onset blind subjects were impaired when crossing the arms to a similar extent as non-blind subjects. These results suggest that the associations between tactile signals and visuospatial representation is maintained once it is accomplished during infancy. Some research studies have also found that the subjects showed reduced deficit in tactile temporal order judgments when the arms were crossed behind their back than when they were crossed in front.

Physiological associations

Tachypsychia

Tachypsychia is a neurological condition that alters the perception of time, usually induced by physical exertion, drug use, or a traumatic event. For someone affected by tachypsychia, time perceived by the individual either lengthens, making events appear to slow down, or contracts, with objects appearing as moving in a speeding blur.

Effects of emotional states

Awe

Research has suggested the feeling of awe has the ability to expand one's perceptions of time availability. Awe can be characterized as an experience of immense perceptual vastness that coincides with an increase in focus. Consequently, it is conceivable that one's temporal perception would slow down when experiencing awe. The perception of time can differ as people choose between savoring moments and deferring gratification.

Fear

Possibly related to the oddball effect, research suggests that time seems to slow down for a person during dangerous events (such as a car accident, a robbery, or when a person perceives a potential predator or mate), or when a person skydives or bungee jumps, where they're capable of complex thoughts in what would normally be the blink of an eye (See Fight-or-flight response). This reported slowing in temporal perception may have been evolutionarily advantageous because it may have enhanced one's ability to intelligibly make quick decisions in moments that were of critical importance to our survival. However, even though observers commonly report that time seems to have moved in slow motion during these events, it is unclear whether this is a function of increased time resolution during the event, or instead an illusion created by the remembering of an emotionally salient event.

A strong time dilation effect has been reported for perception of objects that were looming, but not of those retreating, from the viewer, suggesting that the expanding discs — which mimic an approaching object — elicit self-referential processes which act to signal the presence of a possible danger. Anxious people, or those in great fear, experience greater "time dilation" in response to the same threat stimuli due to higher levels of epinephrine, which increases brain activity (an adrenaline rush). In such circumstances, an illusion of time dilation could assist an effective escape. When exposed to a threat, three-year-old children were observed to exhibit a similar tendency to overestimate elapsed time.

Research suggests that the effect appears only at the point of retrospective assessment, rather than occurring simultaneously with events as they happened. Perceptual abilities were tested during a frightening experience — a free fall — by measuring people's sensitivity to flickering stimuli. The results showed that the subjects' temporal resolution was not improved as the frightening event was occurring. Events appear to have taken longer only in retrospect, possibly because memories were being more densely packed during the frightening situation.

Other researchers suggest that additional variables could lead to a different state of consciousness in which altered time perception does occur during an event. Research does demonstrate that visual sensory processing increases in scenarios involving action preparation. Participants demonstrated a higher detection rate of rapidly presented symbols when preparing to move, as compared to a control without movement.

People shown extracts from films known to induce fear often overestimated the elapsed time of a subsequently presented visual stimulus, whereas people shown emotionally neutral clips (weather forecasts and stock market updates) or those known to evoke feelings of sadness showed no difference. It is argued that fear prompts a state of arousal in the amygdala, which increases the rate of a hypothesized "internal clock". This could be the result of an evolved defensive mechanism triggered by a threatening situation. Individuals experiencing sudden or surprising events, real or imagined (e.g., witnessing a crime, or believing one is seeing a ghost), may overestimate the duration of the event.

Changes with age

Psychologists have found that the subjective perception of the passing of time tends to speed up with increasing age in humans. This often causes people to increasingly underestimate a given interval of time as they age. This fact can likely be attributed to a variety of age-related changes in the aging brain, such as the lowering in dopaminergic levels with older age; however, the details are still being debated.

Very young children will first experience the passing of time when they can subjectively perceive and reflect on the unfolding of a collection of events. A child's awareness of time develops during childhood, when the child's attention and short-term memory capacities form — this developmental process is thought to be dependent on the slow maturation of the prefrontal cortex and hippocampus.

The common explanation is that most external and internal experiences are new for young children but repetitive for adults. Children have to be extremely engaged (i.e. dedicate many neural resources or significant brain power) in the present moment because they must constantly reconfigure their mental models of the world to assimilate it and manage behaviour properly.

Adults, however, may rarely need to step outside mental habits and external routines. When an adult frequently experiences the same stimuli, such stimuli may seem "invisible" as a result of having already been sufficiently mapped by the brain. This phenomenon is known as neural adaptation. Thus, the brain will record fewer densely rich memories during these frequent periods of disengagement from the present moment. Consequently, the subjective perception is often that time passes by at a faster rate with age.

Proportional to the real time

Let S be subjective time, R be real time, and define both to be zero at birth.

One model proposes that the passage of subjective time relative to actual time is inversely proportional to real time:

${\displaystyle \frac{dS}{dR}=\frac{K}{R}}$

When solved, ${\displaystyle S_2-S_1=K(\log R_2-\log R_1)=K\log \left(R_2/R_1\right)}$.

One day would be approximately 1/4,000 of the life of an 11-year-old, but approximately 1/20,000 of the life of a 55-year-old. This helps to explain why a random, ordinary day may therefore appear longer for a young child than an adult. So a year would be experienced by a 55-year-old as passing approximately 5 times more quickly than a year experienced by an 11-year-old. If long-term time perception is based solely on the proportionality of a person's age, then the following four periods in life would appear to be quantitatively equal: ages 5–10 (1x), ages 10–20 (2x), ages 20–40 (4x), age 40–80 (8x), as the end age is twice the start age. However, this does not work for ages 0–10, which corresponds to ages 10–∞.

Proportional to the subjective time

Lemlich posits that the passage of subjective time relative to actual time is inversely proportional to total subjective time, rather than the total real time:

${\displaystyle \frac{dS}{dR}=\frac{K}{S}}$

When mathematically solved,

${\displaystyle S^2=2KR+C}$

It avoids the issue of infinite subjective time passing from real age 0 to 1 year, as the asymptote can be integrated in an improper integral. Using the initial conditions S = 0 when R = 0 and K > 0,

${\displaystyle S=\sqrt{2KR}}$

${\displaystyle \frac{dS}{dR}=\sqrt{\frac{K}{2R}}}$

This means that time appears to pass in proportion to the square root of the perceiver's real age, rather than directly proportional. Under this model, a 55-year-old would subjectively experience time passing 2+1/4 times more quickly than an 11-year-old, rather than 5 times under the previous. This means the following periods in life would appear to be quantitatively equal: ages 0–1, 1–4, 4–9, 9–16, 16–25, 25–36, 36–49, 49–64, 64–81, 81–100, 100–121.

In a study, participants consistently provided answers that fit this model when asked about time perception at 1/4 of their age, but were less consistent for 1/2 of their age. Their answers suggest that this model is more accurate than the previous one.

A consequence of this model is that the fraction of subjective life remaining is always less than the fraction of real life remaining, but it is always more than one half of real life remaining. This can be seen for ${\displaystyle 0<S<S_f}$ and ${\displaystyle 0<R<R_f}$:

${\displaystyle \frac{1}{2}\left(1-\frac{R}{R_f}\right)<1-\frac{S}{S_f}<1-\frac{R}{R_f}}$

Effects of drugs on time perception

Stimulants such as thyroxine, caffeine, and amphetamines lead to overestimation of time intervals by both humans and rats, while depressants and anesthetics such as barbiturates and nitrous oxide can have the opposite effect and lead to underestimation of time intervals. The level of activity in the brain of neurotransmitters such as dopamine and norepinephrine may be the reason for this. A research on stimulant-dependent individuals (SDI) showed several abnormal time processing characteristics including larger time differences for effective duration discrimination, and overestimating the duration of a relatively long time interval. Altered time processing and perception in SDI could explain the difficulty SDI have with delaying gratification. Another research studied the dose-dependent effect in methamphetamine dependents with short term abstinence and its effects on time perception. Results shows that motor timing but not perceptual timing, was altered in meth dependents, which persisted for at least 3 months of abstinence. Dose-dependent effects on time perception were only observed when short-term abstinent meth abusers processed long time intervals. The study concluded that time perception alteration in meth dependents is task specific and dose dependent.

The effect of cannabis on time perception has been studied with inconclusive results mainly due to methodological variations and the paucity of research. Even though 70% of time estimation studies report over-estimation, the findings of time production and time reproduction studies remain inconclusive. Studies show consistently throughout the literature that most cannabis users self-report the experience of a slowed perception of time. In the laboratory, researchers have confirmed the effect of cannabis on the perception of time in both humans and animals. Using PET Scans it was observed that participants who showed a decrease in cerebellar blood flow (CBF) also had a significant alteration in time sense. The relationship between decreased CBF and impaired time sense is of interest as the cerebellum is linked to an internal timing system.

Effects of body temperature

The chemical clock hypothesis implies a causal link between body temperature and the perception of time.

Past work show that increasing body temperature tends to make individuals experience a dilated perception of time and they perceive durations as shorter than they actually were, ultimately leading them to under-estimate time durations. While decreasing body temperature has the opposite effect – causing participants to experience a condensed perception of time leading them to over-estimate time duration – observations of the latter type were rare. Research establishes a parametric effect of body temperature on time perception with higher temperatures generally producing faster subjective time and vice versa. This is especially seen to be true under changes in arousal levels and stressful events.

Applications

Since subjective time is measurable, through information such as heartbeats or actions taken within a time period, there are analytical applications for time perception.

Social networks

Time perception can be used as a tool in social networks to define the subjective experiences of each node within a system. This method can be used to study characters' psychology in dramas, both film and literature, analyzed by social networks. Each character's subjective time may be calculated, with methods as simple as word counting, and compared to the real time of the story to shed light on their internal states.

Transsaccadic memory

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Transsaccadic_memory 

Transsaccadic memory is the neural process that allows humans to perceive their surroundings as a seamless, unified image despite rapid changes in fixation points. Transsaccadic memory is a relatively new topic of interest in the field of psychology. Conflicting views and theories have spurred several types of experiments intended to explain transsaccadic memory and the neural mechanisms involved.

In many situations, human eyes move repeatedly in rapid, discontinuous steps, focusing on a single point for only a short period of time before moving abruptly to the next point. Rapid eye movements of this type are called saccades. If a video camera were to perform such high speed changes in focal points, the image on screen would be disorienting for a human viewer. In contrast, despite the rapidly changing sensory input to the visual system, the normal experience is of a stable visual world; this is an example of perceptual constancy. Transsaccadic memory is a system that helps maintain this stability despite rapid movement of the eyes.

Theories

Saccade target theory

McConkie's and Currie's saccade target theory is similar to research by Schneider who came up with a similar "reference object theory". Both theories hypothesize that each saccade is preceded by processes in the visual system that chose an object as the target for the next fixation point. The object is usually located in peripheral vision. The object's features are stored as a mental representation in transsaccadic memory for identification of future fixations. These target features are searched for by the visual system when the eye lands on its fixation point, and the physical features are compared to the mental representation of the target object. The theory assumes that visual stability is attained when these processes are successful (when the visual stimuli and the mental representation of the target object match). This process occurs before each saccade. Experiments performed by McConkie to support the role of a saccadic target in transsaccadic memory show two things: first, there is a limited peripheral area where a saccadic target exists, and second, attention is vital in recollection of items in the target area. The experiments involved recalling changes to an image that occurred in the peripheral area. Irwin performed similar experiments in which participants recalled letters that occurred near the target area. Due to confounding factors of the controlled environment in the studies, the involvement of saccade target objects is inferred and not established.

Spatiotopic fusion hypothesis

Many radical views of transsaccadic memory exist. Some are favoured more than others because of the evidence that supports them. One less-accepted theory, Breitmeyer's spatiotopic fusion hypothesis, suggested that successive images are fused based on environmental coordinates and not retinal ones. In other words, our memory stores a sequence of images from our surroundings, and joins the images together to give us a full representation in our brain. The orientation of our retinas do not have an influence on this form of memory. This theoretical form of memory supposedly stores highly detailed representations of the world in a high capacity spatial buffer. Research and experiments by other psychologists provide empirical evidence against these claims.

Dennett

Daniel Dennett argued that the way we think we are seeing the world is, for the most part, an illusion. Part of Dennett's argument is the claim that each of us possess what he calls a "Cartesian theater", in which we believe there is a full representation of the visual world in our mind and that there is a place in the mind where it is observed. According to Dennett, none of this exists. Instead, the only place where a full and rich representation exists is directly on the fovea, and every time a saccade occurs, the information is overwritten. Therefore, there is no such thing as transsaccadic memory. Information previously lost only appears to be retained in visual memory because we can look again. In this way, the outside world acts as a visual memory. Since our eyes are constantly moving, we are not aware that visual inputs are constantly being refreshed to give the illusion of the completed picture we think we are seeing. Dennett makes a distinction between the presence of representation, and the representation of presence. The example he gives regarding this distinction is this: if you were to walk into a room covered in identical portraits of Marilyn Monroe, you would see that there are many of them, but you would not really be seeing them all at once. There would be no detailed representation of each individual portrait just the knowledge that they are present. Dennet's theory raises two relevant questions: 1) How does the visual system detect change in the environment? 2) How much information is retained in each saccade? The proposed answer to these questions lies in several mechanisms that support a high sensitivity to change in each visual fixation. These mechanisms are: retinal adaptation, "pop-out" systems, and motion detectors. The implication of this view is that little information is needed to be retained between each saccade.

Irwin

Irwin's conclusion regarding transsaccadic memory is that there are no separate mechanisms, but that rather it is the same as short-term visual memory. Irwin's experiments showed that people cannot fuse pre-saccadic and post-saccadic images in successive fixations. These results are evidence against spatiotopic fusion. According to Irwin, there is no transsaccadic buffer that holds visual information from one fixation point to the next. Also, transaccadic memory does not hold detailed spatial information, but a more abstract representation. Irwin describes transaccadic memory as an undetailed, limited capacity memory that is relatively long-lasting.

Features

Visual short-term memory

Main article: Visual short-term memory

Many statements have been made concerning the relationship between transsaccadic memory and visual short-term memory. Researchers have noted several similar characteristics between the two systems, leading several to believe that transsaccadic memory is in fact visual short-term memory or a part of visual short-term memory. Transsaccadic memory has a limited capacity of three to four items, a slow decay rate and maskable characteristics. Basically, transsaccadic memory can hold three to four items for each saccade, and the retention of items decays or disappears from consciousness slowly after the presentation of the stimulus. However, once a mask stimulus, such as a blank screen, is presented immediately after the stimulus, the items retained prior to the mask can be replaced and/or eliminated faster by the mask. All of these factors are typical characteristics of visual short-term memory. The content stored in transsaccadic memory are less-image like, more abstract and are sparse representations of the objects, which is found to be similar to the type of representations in visual short-term memory. Transsaccadic memory is different from visual short-term memory in that it takes into account the changes of the target's location due to the eye moving to new saccades. The information retained between saccades do not take into account positional information very well. Nevertheless, relational and identity information are well retained. Prime and colleagues (2006) hypothesize, transsaccadic memory utilizes egocentric mechanisms, like selective attention, to reduce the visual search of the target and allow for spatial information between saccades to be retained and updated by incorporation of information across saccades.

Attention

Main article: Attention

Transsaccadic memory is characterized by the integration of information gathered prior to the execution of a saccade (pre-saccadic) and information gathered after the saccade (post-saccadic stimuli. This involves attention, locating the targets necessary to perform a saccade and continuous updates of the environmental information. Attention occurs prior to the movement of the eyes, therefore it has a strong influence on the location of the saccade, what information is being encoded, remembered across saccades and stored into transsaccadic memory. In order to perform a successful and accurate saccade an individual is required to make an attentional shift to the saccadic target. This attentional shift causes the encoding of information to occur near the saccade target location. Attention to the target of the saccade results in better object identification and an increase in accuracy of identification. As well as, improvement in coding of locational information. Attention is restricted to one saccade target per area. It is impossible to keep attention on a target in one area, while performing another saccade simultaneously in another. This will cause prolonged saccadic latency periods (the time it takes to make a saccade from one area to another), and increased reaction times. However, attention can be distributed around the saccade target, rather than the precise location that will fall on the fovea, allowing for the detection of one or two objects situated around the saccadic target. Kowler (1995) proposed two models to explain the relationship between attention, saccades and transsaccadic memory. The spatial model, states that attention is distributed among the perceptual site (visual field) and the saccadic target during the latency period, which allows for the identification of the saccadic target and object surrounding that area. The temporal model states that attention determines where the saccade will occur and releases a “go” signal to initiate a saccade within that area.

Space constancy

Main article: Saccadic masking

Saccadic suppression is responsible for maintaining a continuous, stable, visual world by reducing visual sensitivity to events occurring before, during and after a saccade. The more complex the background on which the stimulus is presented, the larger the suppression. The increase in saccadic suppression can lead to a decrease in detection of change in the visual field. Saccadic suppression can be linked to the phenomenon of change blindness, in which individuals lack the ability to detect small or large changes within an environment without the aid of directed attention. There are two types of saccadic suppression, with the first concerning the detection of light spot flashes during saccades. The lower the spatial frequency, meaning fewer objects in the visual field of the light flashes, the stronger the saccadic suppression. With fewer items in the visual field it is easier for saccadic suppression to occur. The higher the spatial frequency, which involves more complex objects within the visual field, the less likely there will be saccadic suppression. The second type concerns the detection of image displacement or a change in an image during eye movement. A displacement between saccades would not be detected because the movement of the eye eliminates the signal for the detection of the displacement. The location of the target forms an image feature that is used by the visual system to establish space constancy, which maintains the location of an object in space. Target blanking is used to study visual stability, space constancy and the content of information transferred across saccades. Blanking a target after a saccade eliminates an attempt to make a second saccade, resulting in the visual system failing to find the target information. Stability and constancy across the saccades is broken, as a result, image displacements become easier to detect when blanking occurs during or right after the saccade.

Neural structures

Superior colliculus

A neural structure located behind the lateral geniculate nucleus that is understood to control eye movements. In particular, the deeper layers of the superior colliculus, known as lamina VI and VII, have been found to be involved in initiating and executing saccadic eye movements, which includes the desired speed and direction of the saccade. The cells in these layers are organized in a way that forms a map of the visual field. They are organized according to what direction each cell moves the eye. It has been found that activation of specific cells is directed by where objects in the environment are located in the visual field. Once a new object is detected, the cells that fire the strongest to stimuli within this specific area of the visual field will fire, causing the eyes to move and focus on this object. Although the superior colliculus may not be directly related to memory for objects across saccades, it is directly related to the control of saccades and selection of fixation targets.

V4

This is an area within the visual cortex that has been found to play an important role in the target selection of saccades. In other words, this area is important for determining which objects our eyes shift to when they move. Studies have shown that there is a large amount of activation within the visual area V4 before the saccade even takes place. This occurs in the form of shrinking receptive fields. The receptive fields of these brain cells tend to shift towards the object that the eye is about to move towards, generally more so if the object is close to the original fixation point. This dynamic change in receptive fields is thought to enhance the perception and recognition of objects in a visual scene. Because the receptive fields become smaller around the targeted objects, attention within the visual scene is very focused on these objects. Increased attention to target objects within a visual scene help direct eye movements from one object to another. Understanding of the visual scene becomes more efficient because these attention shifts guide the eyes towards relevant objects as opposed to objects that may not be as important.

Lateral intraparietal cortex

The lateral intraparietal cortex (LIP) is an area that is believed to be primarily responsible for keeping an image fluid and undistorted during a saccade (visual/spatial constancy). Past work has shown that the LIP stores information of objects before the saccade (presaccadic), which is then followed by a shift in the receptive fields of the brain cells of this area to compensate for the displacement of the retina during a saccade. This shift in the receptive fields occurs nearly 80 ms before the saccade. The LIP uses quantitative spatial information in order to achieve this shift, which allows for the perception of visual and spatial constancy. The receptive fields of the LIP are quite large and therefore are not well suited to hold details about the perceived objects in the scene during a saccade. This is why objects may seem somewhat blurry during eye movements.

Posterior parietal cortex

The posterior parietal cortex (PPC) is a cortical area that is located in front of the parieto-occipital sulcus and is known to play a role in spatial awareness for eye and arm movements. A study using transcranial magnetic stimulation (TMS) found that the PPC also plays an important role in the amount of information held across saccades. It is believed that transsaccadic memory has the ability to hold roughly three to four items across each saccade with a fully functional PPC. When the PPC is temporarily disrupted, especially the PPC of the right hemisphere, memory across saccades is significantly weakened. Disruption of the PPC leads to a reduction in the ability to store items from a span of three or four, to one item. Further research needs to be conducted in order to fully understand how the PPC is synthesized with object recognition within transsaccadic memory.

Experiments

Random dot pattern

Irwin's early experiments tested participants ability to identify random dot patterns as the same, or as different across saccades. The control condition for this experiment presented dot patterns in the same spatial location without saccades, meaning participants had a single fixation point. A no-overlap control condition presented dot patterns in different spatial locations, while participants maintained fixation on one point. This tested the ability of visual short-term memory in identifying two individual patterns. The experimental condition showed dot patterns in the same spatial location but were viewed at separate fixations, forcing the use of transsaccadic memory. For the experimental condition, participants underwent a calibration phase, where they were shown five points in separate location to fixate on individually, for less than two seconds. The next phase presented a single fixation point for less than two seconds, which was followed by a random dot pattern presented in a different location, acting as a saccade target. The dot pattern disappeared when the saccade was initiated. Another dot pattern then appeared in the same location. Participants had to identify whether the two patterns were the same or different. Results of the experiment showed performance of the experimental condition to be slightly less accurate than the no-overlap condition. Irwin attributed this decrease in accuracy to the extra neural processes involved in performing an eye movement, combined with processing the dot pattern. He concluded from this that transsaccadic memory does exist, but that it is very similar if not identical to short term visual memory and less similar to sensory memory.

Saccade target experiment

The next step for Irwin was to determine if transsaccadic memory is tied to spatial position. He performed experiments using dot patterns and later, performed the same type of experiment alongside McConkie in his effort to prove the saccade target hypothesis. In those experiments, the researchers used a picture instead of dot patterns. Participants in the experimental condition were given an initial eye position, followed by a saccade target position on the picture. Unlike Irwin's first experiment, where the pattern did not change spatial location during the saccade, the picture underwent one of three shift conditions: All shift down, target object shift down, or background shift up. Detection of change ended up being much higher when only the target object moved compared to when the entire image shifted. This demonstrated the importance of the target object in detection of image displacements.

Drawing attention to an eccentric target

Kowler and colleagues were among many to test the relationship between attention and saccades. In one of their first experiments they hypothesized that the initiation of saccades required a signal that would determine which point in space would be the target for the saccade. They questioned whether the signal was attributed to attention or if saccades held their own independent filter. If attention was what decided the location of the target then the saccade latency period would be longer for saccades made away from the target. Additional time would be required to shift attention away from the false target to the correct target. The apparatus was constructed of eight letters arranged around the perimeter of a circle with a cross fixated at the center. Three frames were presented at each trial, the first called the pre-mask held eight letters for 500 ms, the second, labeled critical frame contained seven characters and a numerical (0-9) saccade target and was held for 200 ms. The last frame, post-mask, contained all of the letters. Each trial the identity of the letters, numerical saccade target and the location of the numerical saccade target were chosen at random and blind to the participants. Participants focused on the cross fixation and pressed a button at the start of the trial. After 100 ms a sequence of the three frames were presented, participants were then instructed to make a saccade to either the numerical saccade target or to an opposite character. Once the saccade target was identified participants pressed a button. Results supported the hypothesis, showing that directed attention towards the saccade target made the target easier to identify, decreased latency period and improved on accuracy.

Transsaccadic memory of multiple objects

Prime, Crawford and Vesia (2008) performed an experiment using a TMS in order to understand what structure or structures play a role in transsaccadic memory. It was found that transsaccadic memory was disrupted when TMS stimulation was delivered to the right posterior parietal cortex (rPPC) around the time of a saccade. Prime et al. hypothesized that TMS interfered with the normal spatial remapping operations of the rPPC, in particular the parietal eye fields, that occur during a saccade.

Haptic technology

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Haptic_technology

Haptic technology (also kinaesthetic communication or 3D touch) is technology that can create an experience of touch by applying forces, vibrations, or motions to the user. These technologies can be used to create virtual objects in a computer simulation, to control virtual objects, and to enhance remote control of machines and devices (telerobotics). Haptic devices may incorporate tactile sensors that measure forces exerted by the user on the interface. The word haptic, from the Greek: ἁπτικός (haptikos), means "tactile, pertaining to the sense of touch". Simple haptic devices are common in the form of game controllers, joysticks, and steering wheels.

Haptic technology facilitates investigation of how the human sense of touch works by allowing the creation of controlled haptic virtual objects. Most researchers distinguish three sensory systems related to sense of touch in humans: cutaneous, kinaesthetic and haptic. All perceptions mediated by cutaneous and kinaesthetic sensibility are referred to as tactual perception. The sense of touch may be classified as passive and active, and the term "haptic" is often associated with active touch to communicate or recognize objects.

History

One of the earliest applications of haptic technology was in large aircraft that use servomechanism systems to operate control surfaces. In lighter aircraft without servo systems, as the aircraft approached a stall, the aerodynamic buffeting (vibrations) was felt in the pilot's controls. This was a useful warning of a dangerous flight condition. Servo systems tend to be "one-way", meaning external forces applied aerodynamically to the control surfaces are not perceived at the controls, resulting in the lack of this important sensory cue. To address this, the missing normal forces are simulated with springs and weights. The angle of attack is measured, and as the critical stall point approaches a stick shaker is engaged which simulates the response of a simpler control system. Alternatively, the servo force may be measured and the signal directed to a servo system on the control, also known as force feedback. Force feedback has been implemented experimentally in some excavators and is useful when excavating mixed material such as large rocks embedded in silt or clay. It allows the operator to "feel" and work around unseen obstacles.

In the 1960s, Paul Bach-y-Rita developed a vision substitution system using a 20x20 array of metal rods that could be raised and lowered, producing tactile "dots" analogous to the pixels of a screen. People sitting in a chair equipped with this device could identify pictures from the pattern of dots poked into their backs.

The first US patent for a tactile telephone was granted to Thomas D. Shannon in 1973. An early tactile man-machine communication system was constructed by A. Michael Noll at Bell Telephone Laboratories, Inc. in the early 1970s and a patent was issued for his invention in 1975.

Aura Interactor vest

In 1994, the Aura Interactor vest was developed. The vest is a wearable force-feedback device that monitors an audio signal and uses electromagnetic actuator technology to convert bass sound waves into vibrations that can represent such actions as a punch or kick. The vest plugs into the audio output of a stereo, TV, or VCR and the audio signal is reproduced through a speaker embedded in the vest.

Jensen's Tap-in device

In 1995, Thomas Massie developed the PHANToM (Personal HAptic iNTerface Mechanism) system. It used thimble-like receptacles at the end of computerized arms into which a person's fingers could be inserted, allowing them to "feel" an object on a computer screen.

In 1995, Norwegian Geir Jensen described a wristwatch haptic device with a skin tap mechanism, termed Tap-in. The wristwatch would connect to a mobile phone via Bluetooth, and tapping-frequency patterns would enable the wearer to respond to callers with selected short messages.

In 2015, the Apple Watch was launched. It uses skin tap sensing to deliver notifications and alerts from the mobile phone of the watch wearer.

Types of mechanical touch sensing

Human sensing of mechanical loading in the skin is managed by Mechanoreceptors. There are a number of types of mechanoreceptors but those present in the finger pad are typically placed into two categories. Fast acting (FA) and slow acting (SA). SA mechanoreceptors are sensitive to relatively large stresses and at low frequencies while FA mechanoreceptors are sensitive to smaller stresses at higher frequencies. The result of this is that generally SA sensors can detect textures with amplitudes greater than 200 micrometers and FA sensors can detect textures with amplitudes less than 200 micrometers down to about 1 micrometer, though some research suggests that FA can only detect textures smaller than the fingerprint wavelength. FA mechanoreceptors achieve this high resolution of sensing by sensing vibrations produced by friction and an interaction of the fingerprint texture moving over fine surface texture.

Implementation

See the sub-sections under applications for examples.

Haptic feedback

Haptic feedback (often shortened to just haptics) is controlled vibrations at set frequencies and intervals to provide a sensation representative of an in-game action; this includes 'bumps', 'knocks', and 'tap' of one's hand or fingers.

The majority of electronics offering haptic feedback use vibrations, and most use a type of eccentric rotating mass (ERM) actuator, consisting of an unbalanced weight attached to a motor shaft. As the shaft rotates, the spinning of this irregular mass causes the actuator and the attached device to shake. Piezoelectric actuators are also employed to produce vibrations, and offer even more precise motion than LRAs, with less noise and in a smaller platform, but require higher voltages than do ERMs and LRAs.

Rumble

See also: DualShock and Rumble Pak

Rumble is a form of haptics, rumble is just vibrating steadily at various frequencies.

Force feedback

Force feedback devices use motors to manipulate the movement of an item held by the user. A common use is in automobile driving video games and simulators, which turn the steering wheel to simulate forces experienced when cornering a real vehicle. Direct-drive wheels, introduced in 2013, are based on servomotors and are the most high-end, for strength and fidelity, type of force feedback racing wheels.

In 2007, Novint released the Falcon, the first consumer 3D touch device with high resolution three-dimensional force feedback. This allowed the haptic simulation of objects, textures, recoil, momentum, and the physical presence of objects in games.

Air vortex rings

Air vortex rings are donut-shaped air pockets made up of concentrated gusts of air. Focused air vortices can have the force to blow out a candle or disturb papers from a few yards away. Both Microsoft Research (AirWave) and Disney Research (AIREAL) have used air vortices to deliver non-contact haptic feedback.

Ultrasound

Focused ultrasound beams can be used to create a localized sense of pressure on a finger without touching any physical object. The focal point that creates the sensation of pressure is generated by individually controlling the phase and intensity of each transducer in an array of ultrasound transducers. These beams can also be used to deliver sensations of vibration, and to give users the ability to feel virtual 3D objects. The first commercially available ultrasound device was the Stratos Explore by Ultrahaptics that consisted of 256-transducer array board and a Leap motion controller for hand tracking

Another form of tactile feed back results from active touch when a human scans (runs their finger over a surface) to gain information about a surfaces texture. A significant amount of information about a surfaces texture on the micro meter scale can be gathered through this action as vibrations resulting from friction and texture activate mechanoreceptors in the human skin. Towards this goal plates can be made to vibrate at an ultrasonic frequency which reduces the friction between the plate and skin.

Electrical stimulation

Electrical muscle stimulation (EMS) and transcutaneous electrical nerve stimulation (TENS) can be used to create haptic sensations in the skin or muscles. Most notable examples include haptic suits Tesla suit, Owo haptic vest and wearable armbands Valkyrie EIR. In addition to improving immersion, e.g. by simulating bullet hits, these technologies are sought to create sensations similar to weight and resistance, and can promote muscle training.

Applications

Automotive

With the introduction of large touchscreen control panels in vehicle dashboards, haptic feedback technology is used to provide confirmation of touch commands without needing the driver to take their eyes off the road. Additional contact surfaces, for example the steering wheel or seat, can also provide haptic information to the driver, for example, a warning vibration pattern when close to other vehicles.

Art

Haptic technologies have been explored in virtual arts, such as sound synthesis or graphic design, that make some loose vision and animation. Haptic technology was used to enhance existing art pieces in the Tate Sensorium exhibit in 2015. In music creation, Swedish synthesizer manufacturer Teenage Engineering introduced a haptic subwoofer module for their OP-Z synthesizer allowing musicians to feel the bass frequencies directly on their instrument.

Aviation

Force-feedback can be used to increase adherence to a safe flight envelope and thus reduce the risk of pilots entering dangerous states of flights outside the operational borders while maintaining the pilots' final authority and increasing their situation awareness.

Medicine and dentistry

Haptic interfaces for medical simulation are being developed for training in minimally invasive procedures such as laparoscopy and interventional radiology, and for training dental students. A Virtual Haptic Back (VHB) was successfully integrated in the curriculum at the Ohio University College of Osteopathic Medicine. Haptic technology has enabled the development of telepresence surgery, allowing expert surgeons to operate on patients from a distance. As the surgeon makes an incision, they feel tactile and resistance feedback as if working directly on the patient.

Haptic technology can also provide sensory feedback to ameliorate age-related impairments in balance control and prevent falls in the elderly and balance-impaired. Haptic Cow and Horse are used in veterinary training.

Mobile devices

Vibramotor of LG Optimus L7 II

Tactile haptic feedback is common in cellular devices. In most cases, this takes the form of vibration response to touch. Alpine Electronics uses a haptic feedback technology named PulseTouch on many of their touch-screen car navigation and stereo units. The Nexus One features haptic feedback, according to their specifications. Samsung first launched a phone with haptics in 2007.

Surface haptics refers to the production of variable forces on a user's finger as it interacts with a surface such as a touchscreen.

Notable introductions include:

• Tanvas uses an electrostatic technology to control the in-plane forces experienced by a fingertip, as a programmable function of the finger's motion. The TPaD Tablet Project uses an ultrasonic technology to modulate the apparent slipperiness of a glass touchscreen.
• In 2013, Apple Inc. was awarded the patent for a haptic feedback system that is suitable for multitouch surfaces. Apple's U.S. Patent for a "Method and apparatus for localization of haptic feedback" describes a system where at least two actuators are positioned beneath a multitouch input device, providing vibratory feedback when a user makes contact with the unit. Specifically, the patent provides for one actuator to induce a feedback vibration, while at least one other actuator uses its vibrations to localize the haptic experience by preventing the first set of vibrations from propagating to other areas of the device. The patent gives the example of a "virtual keyboard," however, it is also noted that the invention can be applied to any multitouch interface. Apple's iPhones (and MacBooks) featuring the "Taptic Engine", accomplish their vibrations with a linear resonant actuator (LRA), which moves a mass in a reciprocal manner by means of a magnetic voice coil, similar to how AC electrical signals are translated into motion in the cone of a loudspeaker. LRAs are capable of quicker response times than ERMs, and thus can transmit more accurate haptic imagery.

Neurorehabilitation

For individuals with upper limb motor dysfunction, robotic devices utilizing haptic feedback could be used for neurorehabilitation. Robotic devices, such as end-effectors, and both grounded and ungrounded exoskeletons have been designed to assist in restoring control over several muscle groups. Haptic feedback applied by these robotic devices helps in the recovery of sensory function due to its more immersive nature.

Puzzles

Haptic puzzles have been devised in order to investigate goal-oriented haptic exploration, search, learning and memory in complex 3D environments. The goal is to both enable multi-fingered robots with a sense of touch, and gain more insights into human meta-learning.

Personal computers

In 2015, Apple Inc.'s MacBook and MacBook Pro started incorporating a "Tactile Touchpad" design with button functionality and haptic feedback incorporated into the tracking surface.

Robotics

Haptic feedback is essential to perform complex tasks via telepresence. The Shadow Hand, an advanced robotic hand, has a total of 129 touch sensors embedded in every joint and finger pad that relay information to the operator. This allows tasks such as typing to be performed from a distance. An early prototype can be seen in NASA's collection of humanoid robots, or robonauts.

Sensory substitution

Main article: Sensory substitution

In December 2015 David Eagleman demonstrated a wearable vest that "translates" speech and other audio signals into series of vibrations, this allowed hear-impaired people to "feel" sounds on their body, it has since been made commercially as a wristband.

Space

The use of haptic technologies may be useful in space exploration, including visits to the planet Mars, according to news reports.

Tactile electronic displays

See also: Braille terminal and Braille e-book

A tactile electronic display is a display device that delivers text and graphical information using the sense of touch. Devices of this kind have been developed to assist blind or deaf users by providing an alternative to visual or auditory sensation.

Teleoperators and simulators

Teleoperators are remote controlled robotic tools. When the operator is given feedback on the forces involved, this is called haptic teleoperation. The first electrically actuated teleoperators were built in the 1950s at the Argonne National Laboratory by Raymond Goertz to remotely handle radioactive substances. Since then, the use of force feedback has become more widespread in other kinds of teleoperators, such as remote-controlled underwater exploration devices.

Devices such as medical simulators and flight simulators ideally provide the force feedback that would be felt in real life. Simulated forces are generated using haptic operator controls, allowing data representing touch sensations to be saved or played back.

Teledildonics

Haptic feedback is used within teledildonics, or "sex-technology", in order to remotely connect sex toys and allow users to engage in virtual sex or allow a remote server to control their sex toy. The term was first coined by Ted Nelson in 1975, when discussing the future of love, intimacy and technology. In recent years, teledildonics and sex-technology have expanded to include toys with a two-way connection that allow virtual sex through the communication of vibrations, pressures and sensations. Many "smart" vibrators allow for a one-way connection either between the user, or a remote partner, to allow control of the toy.

Video games

Rumble packs for controllers, such as this Dreamcast Jump Pack, provide haptic feedback through users' hands.

Haptic feedback is commonly used in arcade games, especially racing video games. In 1976, Sega's motorbike game Moto-Cross, also known as Fonz, was the first game to use haptic feedback, causing the handlebars to vibrate during a collision with another vehicle. Tatsumi's TX-1 introduced force feedback to car driving games in 1983. The game Earthshaker! added haptic feedback to a pinball machine in 1989.

Simple haptic devices are common in the form of game controllers, joysticks, and steering wheels. Early implementations were provided through optional components, such as the Nintendo 64 controller's Rumble Pak in 1997. In the same year, the Microsoft SideWinder Force Feedback Pro with built-in feedback was released by Immersion Corporation. Many console controllers and joysticks feature built-in feedback devices, which are motors with unbalanced weights that spin, causing it to vibrate, including Sony's DualShock technology and Microsoft's Impulse Trigger technology. Some automobile steering wheel controllers, for example, are programmed to provide a "feel" of the road. As the user makes a turn or accelerates, the steering wheel responds by resisting turns or slipping out of control.

Notable introductions include:

• 2013: The first direct-drive wheel for sim racing is introduced.
• 2014: A new type of haptic cushion that responds to multimedia inputs by LG Electronics.
• 2015: Steam Machines (console-like PCs) by Valve include a new Steam Controller that uses weighted electromagnets capable of delivering a wide range of haptic feedback via the unit's trackpads. These controllers' feedback systems are user-configurable, delivering precise feedback with haptic force actuators on both sides of the controller.
• 2017: The Nintendo Switch's Joy-Con introduced the HD Rumble feature, developed with Immersion Corporation and using Alps actuators.
• 2018: The Razer Nari Ultimate, gaming headphones using a pair of wide frequency haptic drivers, developed by Lofelt.
• 2020: The Sony PlayStation 5 DualSense controllers supports vibrotactile haptic provided by voice coil actuators integrated in the palm grips, and force feedback for the Adaptive Triggers provided by two DC rotary motors. The actuators in the hand grip are able to give varied and intuitive feedback about in-game actions; for example, in a sandstorm, you can feel the wind and sand, and the motors in the Adaptive Triggers support experiences such as virtually drawing an arrow from a bow.
• 2021, SuperTuxKart 1.3 was released, it has support for force feedback. Force feedback is extremely uncommon for free software games.

Virtual reality

Haptics are gaining widespread acceptance as a key part of virtual reality systems, adding the sense of touch to previously visual-only interfaces. Systems are being developed to use haptic interfaces for 3D modeling and design, including systems that allow holograms to be both seen and felt. Several companies are making full-body or torso haptic vests or haptic suits for use in immersive virtual reality to allow users to feel explosions and bullet impacts.

Chronostasis

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Chronostasis 

Chronostasis (from Greek χρόνος, chrónos, "time" and στάσις, stásis, "standing") is a type of temporal illusion in which the first impression following the introduction of a new event or task-demand to the brain can appear to be extended in time. For example, chronostasis temporarily occurs when fixating on a target stimulus, immediately following a saccade (i.e., quick eye movement). This elicits an overestimation in the temporal duration for which that target stimulus (i.e., postsaccadic stimulus) was perceived. This effect can extend apparent durations by up to half a second and is consistent with the idea that the visual system models events prior to perception.

A common occurrence of this illusion is known as the stopped-clock illusion, where the second hand of an analog clock appears to stay still for longer than normal when looking at it for the first time.

This illusion can also occur in the auditory and tactile domain. For instance, a study suggests that when someone listens to a ringing tone through a telephone, while repetitively switching the receiver from one ear to the other, it causes the caller to overestimate the temporal duration between rings.

Mechanism of action

Overall, chronostasis occurs as a result of a disconnection in the communication between visual sensation and perception. Sensation, information collected from our eyes, is usually directly interpreted to create our perception. This perception is the collection of information that we consciously interpret from visual information. However, quick eye movements known as saccades disrupt this flow of information. Because research into the neurology associated with visual processing is ongoing, there is renewed debate regarding the exact timing of changes in perception that lead to chronostasis. However, below is a description of the general series of events that lead to chronostasis, using the example of a student looking up from his desk toward a clock in the classroom.

A timeline of the sensation and perception of chronostasis within the context of a student in a classroom

1. The eyes receive information from the environment regarding one particular focus. This sensory input is sent directly to the visual cortex to be processed. After visual processing, we consciously perceive this object of focus. In the context of a student in a classroom, the student's eyes focus on a paper on their desk. After his eyes collect light reflected off of the paper and this information is processed in his visual cortex, the student consciously perceives the paper in front of him.
2. Following either a conscious decision or an involuntary perception of a stimulus in the periphery of the visual field, the eyes intend to move to a second target of interest. For the student described above, this may occur as he decides that he wishes to check the clock at the front of the classroom.
3. The muscles of the eye contract and it begins to quickly move towards the second object of interest through an action known as a saccade. As soon as this saccade begins, a signal is sent from the eye back to the brain. This signal, known as an efferent cortical trigger or efference copy, communicates to the brain that a saccade is about to begin. During saccades, the sensitivity of visual information collected by the eyes is greatly reduced and, thus, any image collected during this saccade is very blurry. In order to prevent the visual cortex from processing blurred sensory information, visual information collected by the eyes during a saccade is suppressed through a process known as saccadic masking. This is also the same mechanism used to prevent the experience of motion blur.
4. Following the completion of the saccade, the eyes now focus on the second object of interest. As soon as the saccade concludes, another efferent cortical trigger is sent from the eyes back to the brain. This signal communicates to the brain that the saccade has concluded. Prompted by this signal, the visual cortex once again resumes processing visual information. For the student, his eyes have now reached the clock and his brain's visual cortex begins to process information from his eyes. However, this second efferent trigger also communicates to the brain that a period of time has been missing from perception. To fill this gap in perception, visual information is processed in a manner known as neural antedating or backdating. In this visual processing, the gap in perception is "filled in" with information gathered after the saccade. For the student, the gap of time that occurred during the saccade is substituted with the processed image of the clock. Thus, immediately following the saccade, the second hand of the clock appears to stop in place before moving.

In studying chronostasis and its underlying causes, there is potential bias in the experimental setting. In many experiments, participants are asked to perform some sort of task corresponding to sensory stimuli. This could cause the participants to anticipate stimuli, thus leading to bias. Also, many mechanisms involved in chronostasis are complex and difficult to measure. It is difficult for experimenters to observe the perceptive experiences of participants without "being inside their mind." Furthermore, experimenters normally do not have access to the neural circuitry and neurotransmitters located inside the braincases of their subjects.

Modulating factors

Because of its complexity, there are various characteristics of stimuli and physiological actions that can alter the way one experiences chronostasis.

Saccadic amplitude

The greater the amplitude (or duration) of a saccade, the more severe the resulting overestimation. The further the student in the above example's eyes must travel in order to reach the clock, the more dramatic his perception of chronostasis. This connection supports the assertion that overestimation occurs in order to fill in the length of time omitted by saccadic masking. This would mean that, if the saccade lasted for a longer period of time, there would be more time that needed to be filled in with overestimation.

Attention redirection

When shifting focus from one object to a second object, the saccadic movement of one's eyes is also accompanied by a conscious shift of attention. In the context of the stopped clock illusion, not only do your eyes move, but you also shift your attention to the clock. This led researchers to question whether the movement of the eyes or simply the shift of the observer's attention towards the second stimulus initiated saccadic masking. Experiments in which subjects diverted only their attention without moving their eyes revealed that the redirection of attention alone was not enough to initiate chronostasis. This suggests that attention is not the time marker used when perception is filled back in. Rather, the physical movement of the eyes themselves serves as this critical marker. However, this relationship between attention and perception in the context of chronostasis is often difficult to measure and may be biased in a laboratory setting. Because subjects may be biased as they are instructed to perform actions or to redirect their attention, the concept of attention serving as a critical time marker for chronostasis may not be entirely dismissed.

Spatial continuity

Following investigation, one may wonder if chronostasis still occurs if the saccadic target is moving. In other words, would you still experience chronostasis if the clock you looked at were moving? Through experimentation, researchers found that the occurrence of chronostasis in the presence of a moving stimulus was dependent on the awareness of the subject. If the subject were aware that the saccadic target was moving, they would not experience chronostasis. Conversely, if the subject were not aware of the saccadic target's movement, they did experience chronostasis. This is likely because antedating does not occur in the case of a consciously moving target. If, after the saccade, the eye correctly falls on the target, the brain assumes this target has been at this location throughout the saccade. If the target changes position during the saccade, the interruption of spatial continuity makes the target appear novel.

Stimulus properties

Properties of stimuli themselves have shown to have significant effects on the occurrence of chronostasis. In particular, the frequency and pattern of stimuli affect the observer's perception of chronostasis. In regard to frequency, the occurrence of many, similar events can exaggerate duration overestimation and makes the effects of chronostasis more severe. In regard to repetition, repetitive stimuli appear to be of shorter subjective duration than novel stimuli. This is due to neural suppression within the cortex. Investigation using various imaging techniques has shown that repetitive firing of the same cortical neurons cause them to be suppressed over time. This occurs as a form of neural adaptation.

Sensory domain

The occurrence of chronostasis extends beyond the visual domain into the auditory and tactile domains. In the auditory domain, chronostasis and duration overestimation occur when observing auditory stimuli. One common example is a frequent occurrence when making telephone calls. If, while listening to the phone's ring tone, research subjects move the phone from one ear to the other, the length of time between rings appears longer. In the tactile domain, chronostasis has persisted in research subjects as they reach for and grasp objects. After grasping a new object, subjects overestimate the time in which their hand has been in contact with this object. In other experiments, subjects turning a light on with a button were conditioned to experience the light before the button press. This suggests that, much in the same way subjects overestimate the duration of the second hand as they watch it, they may also overestimate the duration of auditory and tactile stimuli. This has led researchers to investigate the possibility that a common timing mechanism or temporal duration scheme is used for temporal perception of stimuli across a variety of sensory domains.

Indigenous Peoples' Day (United States)

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Indigenous_Peoples%27_Day_(United_States)

 

Indigenous Peoples' Day
Celebration in Berkeley, California, 2012
Also called	First People's Day or Native American Day
Observed by	Various states and municipalities in the Americas on the second Monday in October, in lieu of Columbus Day
Type	Ethnic
Significance	A day in honor of Native Indigenous Americans in opposition to the celebration of Columbus Day.
Date	Varies
Frequency	Annual
First time	October 11, 1992
Related to	National Indigenous Peoples Day in Canada

Indigenous Peoples' Day is a holiday in the United States that celebrates and honors indigenous American peoples and commemorates their histories and cultures. It is celebrated across the United States on the second Monday in October, and is an official city and state holiday in various localities. It began as a counter-celebration held on the same day as the U.S. federal holiday of Columbus Day, which honors Italian explorer Christopher Columbus. Many people do not observe Columbus Day at all, citing the lasting harm Indigenous tribes suffered because of Columbus's contributions to the European colonization of the Americas.

Indigenous Peoples Day was instituted in Berkeley, California, in 1992, to coincide with the 500th anniversary of the arrival of Columbus in the Americas on October 12, 1492. Two years later, Santa Cruz, California, instituted the holiday. Starting in 2014, many other cities and states adopted the holiday. In 2021, Joe Biden formally commemorated the holiday with a presidential proclamation, becoming the first U.S. president to do so, and presidential proclamations have also been issued in 2022 and 2023.

History

In 1977, the International Conference on Discrimination Against Indigenous Populations in the Americas, sponsored by the United Nations in Geneva, Switzerland, began to discuss replacing Columbus Day in the Americas with a celebration to be known as Indigenous Peoples Day. Similarly, Native American groups staged a sort of protest in Boston instead of Thanksgiving, which has been celebrated there to mark collaboration between Massachusetts colonists and Native Americans in the first years. In July 1990, at the First Continental Conference on 500 Years of Indian Resistance in Quito, Ecuador, representatives of indigenous people throughout the Americas agreed that they would mark 1992, the 500th anniversary of the first of the voyages of Christopher Columbus, as a year to promote "continental unity" and "liberation".

After the conference, attendees from Northern California organized protests against the "Quincentennial Jubilee" that had been organized by the United States Congress for the San Francisco Bay Area on Columbus Day in 1992. It was to include replicas of Columbus's ships sailing under the Golden Gate Bridge and reenacting their "discovery" of America. The delegates formed the Bay Area Indian Alliance and in turn, the "Resistance 500" task force. It promoted the idea that Columbus's "discovery" of inhabited lands and the subsequent European colonization of them had resulted in the genocide of thousands of indigenous peoples because of the decisions which were made by colonial and national governments.

In 1992, the group convinced the city council of Berkeley, California, to declare October 12 as a "Day of Solidarity with Indigenous People" and 1992 as the "Year of Indigenous People". The city implemented related programs in schools, libraries, and museums. The city symbolically renamed Columbus Day as "Indigenous Peoples Day" beginning in 1992 to protest the historical conquest of North America by Europeans, and to call attention to the losses suffered by the Native American peoples and their cultures through diseases, warfare, massacres, and forced assimilation. Get Lost (Again) Columbus, an opera by a Native American composer, White Cloud Wolfhawk, was produced that day. Berkeley has celebrated Indigenous Peoples Day ever since. Beginning in 1993, Berkeley has also held an annual pow wow and festival on Indigenous Peoples Day.

In the years following Berkeley's action, other local governments and institutions have either renamed or canceled Columbus Day, either to celebrate Native American history and cultures, to avoid celebrating Columbus and the European colonization of the Americas, or due to raised controversy over the legacy of Columbus. Several other California cities, including Richmond, Santa Cruz, and Sebastopol, now celebrate Indigenous Peoples Day and encourage people to donate to a neighboring tribe and recognize the trauma and pain indigenous peoples have been subjected to by colonizers.

At least twelve states do not celebrate Columbus Day (Alaska, Hawaii, Iowa, Louisiana, Maine, Michigan, New Mexico, North Carolina, Oregon, South Dakota, Vermont, Wisconsin), as well as Washington, DC; South Dakota officially celebrates Native American Day instead. Various tribal governments in Oklahoma designate the day as "Native American Day", or have renamed the day after their own tribes. In 2013, the California state legislature considered a bill, AB55, to formally replace Columbus Day with Native American Day but did not pass it. While the California governor has recognized Indigenous Peoples Day, the holiday was eliminated by Governor Arnold Schwarzenegger in the 2008-12 California budget crisis. On August 30, 2017, following similar affirmative votes in Oberlin, Ohio, followed later by Bangor, Maine, in the earlier weeks of the same month, the Los Angeles City Council voted in favor of replacing Columbus Day with Indigenous Peoples Day. On October 10, 2019, just a few days before Columbus Day would be celebrated in Washington, D.C., the D.C. Council voted to temporarily replace Columbus Day with Indigenous Peoples Day. This bill was led by Councilmember David Grosso (I-At Large) and must undergo congressional approval to become permanent. Washington D.C., as of May 2023, has yet to have given the permanent legislation to this renaming.

Other celebrations

Numerous efforts in North America have honored Native American people as part of Columbus Day, or by designating two holidays for the same date. Especially since Native American activism has increased since the 1960s and 1970s, a variety of protests have been staged against celebrating Columbus Day. These have included mock trials of Christopher Columbus in St. Paul, Minnesota, and protests and disruptions of Columbus Day parades in the United States.

Indigenous peoples in other nations have also lobbied to have holidays established to recognize their contributions and history. In South America, for instance, Brazil celebrates "National Indigenous Peoples Day" on April 19.

In Asia, Taiwan designated August 1 as Indigenous Peoples Day in 2016 under the administration of President Tsai Ing-wen, who announced that the government is committed to promoting the rights of Taiwan's indigenous peoples and enhancing public awareness of their culture and history. In the Philippines, the National Commission on Indigenous Peoples, as well as various local indigenous towns, designated October 29, 1987, as Indigenous Peoples Day.

Native American Day

Main article: Native American Day

Some states celebrate a separate but similar Native American Day; however, this is observed not on Columbus Day but in September. Those who observe include the states of California and Tennessee. However, as of 2021, the State of California does not actually observe this holiday by closing its government offices, giving its employees paid time off, or encouraging private businesses to do the same in observance. In Washington state it is celebrated the Friday immediately following the fourth Thursday in November.

International Day of the World's Indigenous People

Main article: International Day of the World's Indigenous Peoples

In 2003, the United Nations declared an International Day of the World's Indigenous People, establishing it on August 9. This international holiday has been celebrated also in various nations.

Indigenous Peoples Day observers

States in the U.S. that celebrate Indigenous Peoples Day or Native American Day instead of or in addition to Columbus Day

The following U.S. states celebrate Indigenous Peoples Day instead of or in addition to Columbus Day.

Adopted 1988

• Hawaii (celebrated as Discoverers' Day)

Adopted 1989

• South Dakota (celebrated as Native American Day, instead of Columbus Day)

Adopted 2015

• Alaska (celebrated instead of Columbus Day)

Adopted 2016

• Minnesota (stopped celebrating Columbus Day in 2023)
• Vermont (stopped celebrating Columbus Day in 2019)

Adopted 2018

• Iowa
• North Carolina

Adopted 2019

• Alabama (celebrated as American Indian Heritage Day / Columbus Day)
• California
• District of Columbia (celebrated instead of Columbus Day)
• Louisiana
• Maine (celebrated instead of Columbus Day)
• Michigan
• New Mexico (celebrated instead of Columbus Day)
• Oklahoma
• Wisconsin

Adopted 2020

• Nebraska
• Virginia

Adopted 2021

• Oregon
• Texas

Criticism and controversy

Indigenous Peoples' Day has been criticized by some American conservative communities and public figures. In 2020, President Donald Trump criticized Indigenous Peoples' Day at a campaign rally in Michigan, calling it an example of how "the radical left is eradicating our history". In 2022, the Washington Examiner published a column calling for the holiday's end, saying that indigenous peoples attacked and conquered each other's land.