Telepathy

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The Ganzfeld experiments that aimed to demonstrate telepathy have been criticized for lack of replication and poor controls.

Telepathy (from the Greek τῆλε, tele meaning "distant" and πάθος, pathos or -patheia meaning "feeling, perception, passion, affliction, experience") is the purported transmission of information from one person to another without using any known human sensory channels or physical interaction. The term was coined in 1882 by the classical scholar Frederic W. H. Myers, a founder of the Society for Psychical Research, and has remained more popular than the earlier expression thought-transference.

Telepathy experiments have historically been criticized for lack of proper controls and repeatability. There is no convincing evidence that telepathy exists, and the topic is generally considered by the scientific community to be pseudoscience.

Origins of the concept

According to historians such as Roger Luckhurst and Janet Oppenheim the origin of the concept of telepathy in Western civilization can be tracked to the late 19th century and the formation of the Society for Psychical Research. As the physical sciences made significant advances, scientific concepts were applied to mental phenomena (e.g., animal magnetism), with the hope that this would help to understand paranormal phenomena. The modern concept of telepathy emerged in this context.

Psychical researcher Eric Dingwall criticized SPR founding members Frederic W. H. Myers and William F. Barrett for trying to "prove" telepathy rather than objectively analyze whether or not it existed.

Thought reading

In the late 19th century, the magician and mentalist, Washington Irving Bishop would perform "thought reading" demonstrations. Bishop claimed no supernatural powers and ascribed his powers to muscular sensitivity (reading thoughts from unconscious bodily cues). Bishop was investigated by a group of scientists including the editor of the British Medical Journal and the psychologist Francis Galton. Bishop performed several feats successfully such as correctly identifying a selected spot on a table and locating a hidden object. During the experiment Bishop required physical contact with a subject who knew the correct answer. He would hold the hand or wrist of the helper. The scientists concluded that Bishop was not a genuine telepath but using a highly trained skill to detect ideomotor movements.

Another famous thought reader was the magician Stuart Cumberland. He was famous for performing blindfolded feats such as identifying a hidden object in a room that a person had picked out or asking someone to imagine a murder scene and then attempt to read the subject's thoughts and identify the victim and reenact the crime. Cumberland claimed to possess no genuine psychic ability and his thought reading performances could only be demonstrated by holding the hand of his subject to read their muscular movements. He came into dispute with psychical researchers associated with the Society for Psychical Research who were searching for genuine cases of telepathy. Cumberland argued that both telepathy and communication with the dead were impossible and that the mind of man cannot be read through telepathy, but only by muscle reading.

Case studies

Gilbert Murray conducted early telepathy experiments.

In the late 19th century the Creery Sisters (Mary, Alice, Maud, Kathleen, and Emily) were tested by the Society for Psychical Research and believed to have genuine psychic ability. However, during a later experiment they were caught utilizing signal codes and they confessed to fraud. George Albert Smith and Douglas Blackburn were claimed to be genuine psychics by the Society for Psychical Research but Blackburn confessed to fraud:

For nearly thirty years the telepathic experiments conducted by Mr. G. A. Smith and myself have been accepted and cited as the basic evidence of the truth of thought transference... ...the whole of those alleged experiments were bogus, and originated in the honest desire of two youths to show how easily men of scientific mind and training could be deceived when seeking for evidence in support of a theory they were wishful to establish.

Between 1916 and 1924, Gilbert Murray conducted 236 experiments into telepathy and reported 36% as successful, however, it was suggested that the results could be explained by hyperaesthesia as he could hear what was being said by the sender. Psychologist Leonard T. Troland had carried out experiments in telepathy at Harvard University which were reported in 1917. The subjects produced below chance expectations.

Arthur Conan Doyle and W. T. Stead were duped into believing Julius and Agnes Zancig had genuine psychic powers. Both Doyle and Stead wrote the Zancigs performed telepathy. In 1924, Julius and Agnes Zancig confessed that their mind reading act was a trick and published the secret code and all the details of the trick method they had used under the title of Our Secrets!! in a London newspaper.

In 1924, Robert H. Gault of Northwestern University with Gardner Murphy conducted the first American radio test for telepathy. The results were entirely negative. One of their experiments involved the attempted thought transmission of a chosen number, out of 2010 replies none were correct.

In February 1927, with the co-operation of the British Broadcasting Corporation (BBC), V. J. Woolley who was at the time the Research Officer for the SPR, arranged a telepathy experiment in which radio listeners were asked to take part. The experiment involved 'agents' thinking about five selected objects in an office at Tavistock Square, whilst listeners on the radio were asked to identify the objects from the BBC studio at Savoy Hill. 24, 659 answers were received. The results revealed no evidence for telepathy.

A famous experiment in telepathy was recorded by the American author Upton Sinclair in his book Mental Radio which documents Sinclair's test of psychic abilities of Mary Craig Sinclair, his second wife. She attempted to duplicate 290 pictures which were drawn by her husband. Sinclair claimed Mary successfully duplicated 65 of them, with 155 "partial successes" and 70 failures. However, these experiments were not conducted in a controlled scientific laboratory environment. Science writer Martin Gardner suggested that the possibility of sensory leakage during the experiment had not been ruled out:

In the first place, an intuitive wife, who knows her husband intimately, may be able to guess with a fair degree of accuracy what he is likely to draw—particularly if the picture is related to some freshly recalled event the two experienced in common. At first, simple pictures like chairs and tables would likely predominate, but as these are exhausted, the field of choice narrows and pictures are more likely to be suggested by recent experiences. It is also possible that Sinclair may have given conversational hints during some of the tests—hints which in his strong will to believe, he would promptly forget about. Also, one must not rule out the possibility that in many tests, made across the width of a room, Mrs. Sinclair may have seen the wiggling of the top of a pencil, or arm movements, which would convey to her unconscious a rough notion of the drawing.

Frederick Marion who was investigated by the Society for Psychical Research in the late 1930-1940s.

The Turner-Ownbey long distance telepathy experiment was discovered to contain flaws. May Frances Turner positioned herself in the Duke Parapsychology Laboratory whilst Sara Ownbey claimed to receive transmissions 250 miles away. For the experiment Turner would think of a symbol and write it down whilst Ownbey would write her guesses. The scores were highly successful and both records were supposed to be sent to J. B. Rhine; however, Ownbey sent them to Turner. Critics pointed out this invalidated the results as she could have simply written her own record to agree with the other. When the experiment was repeated and the records were sent to Rhine the scores dropped to average.

Another example is the experiment carried out by the author Harold Sherman with the explorer Hubert Wilkins who carried out their own experiment in telepathy for five and a half months starting in October 1937. This took place when Sherman was in New York and Wilkins was in the Arctic. The experiment consisted of Sherman and Wilkins at the end of each day to relax and visualise a mental image or "thought impression" of the events or thoughts they had experienced in the day and then to record those images and thoughts on paper in a diary. The results at the end when comparing Sherman's and Wilkins' diaries were claimed to be more than 60 percent.

The full results of the experiments were published in 1942 in a book by Sherman and Wilkins titled Thoughts Through Space. In the book both Sherman and Wilkins had written they believed they had demonstrated that it was possible to send and receive thought impressions from the mind of one person to another. The magician John Booth wrote the experiment was not an example of telepathy as a high percentage of misses had occurred. Booth wrote it was more likely that the "hits" were the result of "coincidence, law of averages, subconscious expectancy, logical inference or a plain lucky guess". A review of their book in the American Journal of Orthopsychiatry cast doubt on their experiment noting "the study was published five years after it was conducted, arouses suspicion on the validity of the conclusions.

In 1948, on the BBC radio Maurice Fogel made the claim that he could demonstrate telepathy. This intrigued the journalist Arthur Helliwell who wanted to discover his methods. He found that Fogel's mind reading acts were all based on trickery, he relied on information about members of his audience before the show started. Helliwell exposed Fogel's methods in a newspaper article. Although Fogel managed to fool some people into believing he could perform genuine telepathy, the majority of his audience knew he was a showman.

In a series of experiments Samuel Soal and his assistant K. M. Goldney examined 160 subjects over 128,000 trials and obtained no evidence for the existence of telepathy. Soal tested Basil Shackleton and Gloria Stewart between 1941 and 1943 in over five hundred sittings and over twenty thousand guesses. Shackleton scored 2890 compared with a chance expectation of 2308 and Gloria scored 9410 compared with a chance level of 7420. It was later discovered the results had been tampered with. Gretl Albert who was present during many of the experiments said she had witnessed Soal altering the records during the sessions. Betty Marwick discovered Soal had not used the method of random selection of numbers as he had claimed. Marwick showed that there had been manipulation of the score sheets "all the experiments reported by Soal had thereby been discredited."

In 1979 the physicists John G. Taylor and Eduardo Balanovski wrote the only scientifically feasible explanation for telepathy could be electromagnetism (EM) involving EM fields. In a series of experiments the EM levels were many orders of magnitude lower than calculated and no paranormal effects were observed. Both Taylor and Balanovski wrote their results were a strong argument against the validity of telepathy.

Research in anomalistic psychology has discovered that in some cases telepathy can be explained by a covariation bias. In an experiment (Schienle et al. 1996) 22 believers and 20 skeptics were asked to judge the covariation between transmitted symbols and the corresponding feedback given by a receiver. According to the results the believers overestimated the number of successful transmissions whilst the skeptics made accurate hit judgments. The results from another telepathy experiment involving 48 undergraduate college students (Rudski, 2002) were explained by hindsight and confirmation biases.

In parapsychology

Within the field of parapsychology, telepathy is considered to be a form of extrasensory perception (ESP) or anomalous cognition in which information is transferred through Psi. It is often categorized similarly to precognition and clairvoyance. Experiments have been used to test for telepathic abilities. Among the most well known are the use of Zener cards and the Ganzfeld experiment.

Types

Parapsychology describes several forms of telepathy:

• Latent telepathy, formerly known as "deferred telepathy", is described as the transfer of information, through Psi, with an observable time-lag between transmission and reception.
• Retrocognitive, precognitive, and intuitive telepathy is described as being the transfer of information, through Psi, about the past, future or present state of an individual's mind to another individual.
• Emotive telepathy, also known as remote influence or emotional transfer, is the process of transferring kinesthetic sensations through altered states.
• Superconscious telepathy involves tapping into the superconscious to access the collective wisdom of the human species for knowledge.

Zener Cards

Zener cards

Zener cards are marked with five distinctive symbols. When using them, one individual is designated the "sender" and another the "receiver". The sender selects a random card and visualize the symbol on it, while the receiver attempts to determine that symbol using Psi. Statistically, the receiver has a 20% chance of randomly guessing the correct symbol, so to demonstrate telepathy, they must repeatedly score a success rate that is significantly higher than 20%. If not conducted properly, this method can be vulnerable to sensory leakage and card counting.

J. B. Rhine's experiments with Zener cards were discredited due to the discovery that sensory leakage or cheating could account for all his results such as the subject being able to read the symbols from the back of the cards and being able to see and hear the experimenter to note subtle clues. Once Rhine took precautions in response to criticisms of his methods, he was unable to find any high-scoring subjects. Due to the methodological problems, parapsychologists no longer utilize card-guessing studies.

Dream telepathy

Parapsychological studies into dream telepathy were carried out at the Maimonides Medical Center in Brooklyn, New York led by Stanley Krippner and Montague Ullman. They concluded the results from some of their experiments supported dream telepathy. However, the results have not been independently replicated. The psychologist James Alcock has written the dream telepathy experiments at Maimonides have failed to provide evidence for telepathy and "lack of replication is rampant."

The picture target experiments that were conducted by Krippner and Ullman were criticized by C. E. M. Hansel. According to Hansel there were weaknesses in the design of the experiments in the way in which the agent became aware of their target picture. Only the agent should have known the target and no other person until the judging of targets had been completed, however, an experimenter was with the agent when the target envelope was opened. Hansel also wrote there had been poor controls in the experiment as the main experimenter could communicate with the subject.

An attempt to replicate the experiments that used picture targets was carried out by Edward Belvedere and David Foulkes. The finding was that neither the subject nor the judges matched the targets with dreams above chance level. Results from other experiments by Belvedere and Foulkes were also negative.

Ganzfeld experiment

When using the Ganzfeld experiment to test for telepathy, one individual is designated the receiver and is placed inside a controlled environment where they are deprived of sensory input, and another is designated the sender and is placed in a separate location. The receiver is then required to receive information from the sender. The nature of the information may vary between experiments.

The ganzfeld experiment studies that were examined by Ray Hyman and Charles Honorton had methodological problems that were well documented. Honorton reported only 36% of the studies used duplicate target sets of pictures to avoid handling cues. Hyman discovered flaws in all of the 42 ganzfeld experiments and to access each experiment, he devised a set of 12 categories of flaws. Six of these concerned statistical defects, the other six covered procedural flaws such as inadequate documentation, randomization and security as well as possibilities of sensory leakage. Over half of the studies failed to safeguard against sensory leakage and all of the studies contained at least one of the 12 flaws. Because of the flaws, Honorton agreed with Hyman the 42 ganzfeld studies could not support the claim for the existence of psi.

Possibilities of sensory leakage in the ganzfeld experiments included the receivers hearing what was going on in the sender's room next door as the rooms were not soundproof and the sender's fingerprints to be visible on the target object for the receiver to see.

Hyman also reviewed the autoganzfeld experiments and discovered a pattern in the data that implied a visual cue may have taken place:

The most suspicious pattern was the fact that the hit rate for a given target increased with the frequency of occurrence of that target in the experiment. The hit rate for the targets that occurred only once was right at the chance expectation of 25%. For targets that appeared twice the hit rate crept up to 28%. For those that occurred three times it was 38%, and for those targets that occurred six or more times, the hit rate was 52%. Each time a videotape is played its quality can degrade. It is plausible then, that when a frequently used clip is the target for a given session, it may be physically distinguishable from the other three decoy clips that are presented to the subject for judging. Surprisingly, the parapsychological community has not taken this finding seriously. They still include the autoganzfeld series in their meta-analyses and treat it as convincing evidence for the reality of psi.

Hyman wrote the autoganzfeld experiments were flawed because they did not preclude the possibility of sensory leakage. In 2010, Lance Storm, Patrizio Tressoldi, and Lorenzo Di Risio analyzed 29 ganzfeld studies from 1997 to 2008. Of the 1,498 trials, 483 produced hits, corresponding to a hit rate of 32.2%. This hit rate is statistically significant with p < .001. Participants selected for personality traits and personal characteristics thought to be psi-conducive were found to perform significantly better than unselected participants in the ganzfeld condition. Hyman (2010) published a rebuttal to Storm et al. According to Hyman "reliance on meta-analysis as the sole basis for justifying the claim that an anomaly exists and that the evidence for it is consistent and replicable is fallacious. It distorts what scientists mean by confirmatory evidence." Hyman wrote the ganzfeld studies have not been independently replicated and have failed to produce evidence for telepathy. Storm et al. published a response to Hyman claiming the ganzfeld experimental design has proved to be consistent and reliable but parapsychology is a struggling discipline that has not received much attention so further research on the subject is necessary. Rouder et al. 2013 wrote that critical evaluation of Storm et al.'s meta-analysis reveals no evidence for telepathy, no plausible mechanism and omitted replication failures.

A 2016 paper examined questionable research practices in the ganzfeld experiments.

Twin telepathy

Twin telepathy is a belief that has been described as a myth in psychological literature. Psychologists Stephen Hupp and Jeremy Jewell have noted that all experiments on the subject have failed to provide any scientific evidence for telepathy between twins. According to Hupp and Jewell there are various behavioral and genetic factors that contribute to the twin telepathy myth "identical twins typically spend a lot of time together and are usually exposed to very similar environments. Thus, it's not at all surprising that they act in similar ways and are adept at anticipating and forecasting each other's reactions to events."

A 1993 study by Susan Blackmore investigated the claims of twin telepathy. In an experiment with six sets of twins one subject would act as the sender and the other the receiver. The sender was given selected objects, photographs or numbers and would attempt to psychically send the information to the receiver. The results from the experiment were negative, no evidence of telepathy was observed.

The skeptical investigator Benjamin Radford has noted that "Despite decades of research trying to prove telepathy, there is no credible scientific evidence that psychic powers exist, either in the general population or among twins specifically. The idea that two people who shared their mother's womb — or even who share the same DNA — have a mysterious mental connection is an intriguing one not borne out in science."

Scientific reception

A variety of tests have been performed to demonstrate telepathy, but there is no scientific evidence that the power exists. A panel commissioned by the United States National Research Council to study paranormal claims concluded that "despite a 130-year record of scientific research on such matters, our committee could find no scientific justification for the existence of phenomena such as extrasensory perception, mental telepathy or 'mind over matter' exercises... Evaluation of a large body of the best available evidence simply does not support the contention that these phenomena exist." The scientific community considers parapsychology a pseudoscience. There is no known mechanism for telepathy. Philosopher and physicist Mario Bunge has written that telepathy would contradict laws of science and the claim that "signals can be transmitted across space without fading with distance is inconsistent with physics".

Physicist John Taylor has written the experiments that have been claimed by parapsychologists to support evidence for the existence of telepathy are based on the use of shaky statistical analysis and poor design, and attempts to duplicate such experiments by the scientific community have failed. Taylor also wrote the arguments used by parapsychologists for the feasibility of such phenomena are based on distortions of theoretical physics as well as "complete ignorance" of relevant areas of physics.

Psychologist Stuart Sutherland wrote that cases of telepathy can be explained by people underestimating the probability of coincidences. According to Sutherland, "most stories about this phenomenon concern people who are close to one another - husband and wife or brother and sister. Since such people have much in common, it is highly probable that they will sometimes think the same thought at the same time." Graham Reed, a specialist in anomalistic psychology, noted that experiments into telepathy often involve the subject relaxing and reporting the 'messages' to consist of colored geometric shapes. Reed wrote that these are a common type of hypnagogic image and not evidence for telepathic communication.

Outside of parapsychology, telepathy is generally explained as the result of fraud, self-delusion and/or self-deception and not as a paranormal power. Psychological research has also revealed other explanations such as confirmation bias, expectancy bias, sensory leakage, subjective validation and wishful thinking. Virtually all of the instances of more popular psychic phenomena, such as mediumship, can be attributed to non-paranormal techniques such as cold reading. Magicians such as Ian Rowland and Derren Brown have demonstrated techniques and results similar to those of popular psychics, without paranormal means. They have identified, described, and developed psychological techniques of cold reading and hot reading.

Psychiatry

The notion of telepathy is not dissimilar to two clinical concepts: delusions of thought insertion/removal. This similarity might explain how an individual might come to the conclusion that they were experiencing telepathy. Thought insertion/removal is a symptom of psychosis, particularly of schizophrenia, schizoaffective disorder or substance-induced psychosis. Psychiatric patients who experience this symptom falsely believe that some of their thoughts are not their own and that others (e.g., other people, aliens, demons or fallen angels, or conspiring intelligence agencies) are putting thoughts into their minds (thought insertion). Some patients feel as if thoughts are being taken out of their minds or deleted (thought removal). Along with other symptoms of psychosis, delusions of thought insertion may be reduced by antipsychotic medication. Psychiatrists and clinical psychologists believe and empirical findings support the idea that people with schizotypy and schizotypal personality disorder are particularly likely to believe in telepathy.

Use in fiction

Telepathy is a common theme in modern fiction and science fiction, with many extraterrestrials (such as the Protoss in the StarCraft franchise), superheroes, and supervillains having telepathic ability.

How Nanotech Will Help Us Explore Other Planets

Meghan Brown posted on October 15, 2018 

Original link:  https://www.engineering.com/DesignerEdge/DesignerEdgeArticles/ArticleID/17828/How-Nanotech-Will-Help-Us-Explore-Other-Planets.aspx?fbclid=IwAR27eaxHAAp8DCGdXu24diEeUZgbpbjj3plOGSP3LVdktYoPmzyS7EiuJQ0

What’s your favorite science fiction use of nanotechnology?  Are you a fan of the Terminator, or the Borg from Star Trek, that imitate humans or assimilate them?  Or are you fascinated by the replicators in Stargate:SG1, which can self-assemble, self-replicate and take the form of anything from space ships and buildings, to machinery, to humanoid bodies?

Whatever you find most interesting, the constant is that nanotechnology is one of our favorite sci-fi technologies.  What’s even cooler is that, like many technologies, nanotech is quickly becoming more “science” and less “fiction.”  While we’re not at the point of humanoid replicators or self-assembling vehicles just yet, there are a lot of potential application for nanotechnology to improve some of the most ambitious human endeavours—such as space exploration.

Technology at the Nanoscale

What is nanotech exactly?  Short answer, it’s technology that operates at the nanoscale.  One nanometer (nm) is measured at one billionth (10^-9) of a meter, and the convention is to assign the term “nanotechnology” to technology that operates on the scale of 1 to 100 nm.  The 1 nm bottom limit is due to the size of atoms, which nanotech needs to manipulate, while the upper limit is largely arbitrary as the size where nanoscale phenomena become apparent and useable by a nano device.

Nanotechnology features two primary approaches, which are “bottom up” where materials or devices are self-assembled from molecular components, and “top down” where nanoscale objects are constructed by micro-scale and macro-scale devices.  Both methods show potential for the development of future nanomaterials and nanodevices capable of exhibiting specific properties or being programmed to perform tasks and operate autonomously.

With the potential inherent in nanotechnology, it’s easy to see why nanoengineering and nanotechnology research are booming, and a particular focus is on exploring space: how to get there, how to protect space travellers, and where they will live when they arrive on distant planets.

Nanotechnology for Space Exploration

Space exploration is a prime candidate to take advantage of nanotechnology.  It’s expensive and risky, and in many ways currently, extremely inefficient.  Picture the millions spent on space missions, the satellites and astronauts lost, and the sheet investment of time needed for even the simplest endeavor.
 

(Image source: Forbes.com)

These expenses, risks and inefficiencies are what makes nanotechnology so appealing, because the benefits and capabilities that nanotech promises could solve a lot of these problems.

Propulsion

Propulsion is one of the most significant challenges to developing fast and convenient space travel.  Make no mistake, we’ve gotten pretty good at building rockets that go really fast—even fast enough to get into orbit around the planet—but that’s when things slow right down.  While launch rockets are great at what they were designed to do (lift a giant tube away from the planet), they aren’t meant for the slower speed and fuel longevity required for extended travel.  Once a spacecraft wants to leave orbit and journey somewhere else, a different kind of propulsion engine is required.

Solar sails could be the solution, and are one of the technologies that sees a lot of potential in nanotechnology.  As a propulsion device, solar sails use the pressure of solar radiation against a highly reflective expanse of material to create thrust, and therefore don't need additional propellant fuel. However, solar sails do need to have a very large surface area that is extremely reflective, but also extremely thin and lightweight.

The Solar Sail Demonstration mission led by NASA and L’Garde Inc. aimed to prove the viability of using ultra thin sails and sunlight for propulsion. (Image courtesy of NASA.)

Materials engineered using nanotechnology can satisfy these requirements.  Effective solar sails have to be hundreds of meters—or even kilometers—wide in order to have enough surface area to create the necessary propulsion to travel inter-planetary or interstellar distances.  Carbon nanotube-based materials in particular are a nanotechnological solution, able to be made into strong, lightweight and extremely thin sheets that could replace the polymer and aluminum solar sail materials currently used for sail prototypes.  Advanced nanomaterials could also be designed to have specific properties, such as being highly reflective.

There’s also the goal of developing future nanotechnology and nanomaterials that will have self-repairing properties. In the context of solar sails, this could be invaluable; for example, if the nanomaterial could recognize and repair damage sustained during deployment and travel, such as tears during the unfolding process, or “healing” from micrometeorite impacts.  This could drastically improve the success and longevity of these missions, enabling solar sail-propelled spacecraft to travel faster and farther.

Planetary Exploration with Nanobots and Nanosensors

Exploring the surface of a distant planet using swarms of tiny nanorobots is another popular application of nanotech in space.

Currently, the Mars rovers—Spirit, Opportunity and Curiosity—have been the greatest success stories when it comes to planetary exploration.  But as scientifically rich as these missions have been, each rover can only examine one small area at a time, and their movement speeds are quite slow.  It’s understandable, given the time lags involved in communicating between Earth and Mars, and the complexity of the instructions and data that must be relayed back and forth. 

Understandable, but extremely slow.

Low-angle self-portrait of NASA’s Curiosity Mars rover. Taken August 5th, 2015, the image is a composite showing the vehicle and the site where it performed drilling operations, dubbed “Buckskin” on lower Mount Sharpe. Future planetary exploration using nanobots would replace these types of rovers, and provide faster and more detailed mapping, chemical analysis, atmospheric composition and other vital data. (Image courtesy of NASA.)

This is where a nanorobot swarm could be beneficial.  Imagine if a single landed rover could deploy a mass of tiny nanobots capable of travelling across the planet’s surface, or drifting on wind and through the atmosphere, to survey large swaths of a planet quickly and in great detail—even down to the molecular level.

With the development of nanobots that operate using some form of artificial intelligence (AI) that enables them to communicate and self-organize, then the possibilities are almost limitless.  A planetary surface survey mission could see nanobots rolling or crawling across the landscape, collecting sensor data on the minerals and compounds in the air and ground, testing for toxicity or measuring radiation, and then assembling into a communication antenna to transmit the data back to a hub station or satellite for further analysis and relay back to Earth. 

A team from Northeastern University engaged in investigating possible concepts for nanotech in space exploration also proposed the idea of a sensor net “spider web” comprised of hairline tubes that could be deployed to spread across large areas of a planet’s surface.  The tubes would contain a multitude of nanosensors to measure surface temperature, chemical composition and other elements of the planetary environment.

Nanobot swarms could also be effective in exploring the thick atmosphere of planets like Venus, or the stormy gaseous planets such as Jupiter and Saturn, by releasing nanobots or nanosensors into the atmosphere and having them transmit their data back to orbiting satellites, gathering detailed information on wind currents, storm patterns, and chemical composition of these planets.

For these applications of nanorobotics, many researchers are looking to nano electromechanical systems (NEMS) in the place of conventional motor designs.  This is because NEMS can be made of nanomaterials, such as carbon nanotubes, these roots can be made extremely tiny, and extremely flexible.

NEMS are a specific class of device that integrates electrical and mechanical functionality at the nanoscale, and combine transistor-like nanoelectronics with mechanical components such as motors, pumps and actuators.  They are often used as physical, biological or chemical sensors for a variety of applications, such as accelerometer and air chemical sensors. 

Nanomaterials for Enhanced Spacesuits

But travelling to other planets, and exploring them with nanobots, is only half the journey – eventually, humans will want to travel to these planets, and explore the surface for themselves.
Spacesuits enhanced with nanotechnology will be an essential aspect of getting humans safely to other planets, and enabling them to spend time exploring—since, as of yet, there are no planetary surfaces discovered (other than Earth, of course) which have breathable atmosphere, and radiation during space travel and on an extraterrestrial planet’s surface is a constant concern.

Spacesuits made from nanomaterials will be lighter and more flexible, allowing astronauts to explore and maneuver easily.

The potential for self-repairing nanomaterials is once again a key element, as one of the most significant threats facing astronauts is the possibility of puncturing their suit and creating a breach that lets oxygen escape, or lets a toxic atmosphere inside.

At it’s most basic—relatively speaking, since this is still advanced futuristic tech—a spacesuit could have a gel or metallic nanomaterial layer between the interior and exterior surfaces of a spacesuit.  This layer would respond to a puncture or tear by reorganizing or reassembling in order to close or repair the damage.  Those interior and exterior layers are also likely to be fabricated out of advanced metamaterials that have been nanoengineered for exceptional strength and durability, while remaining thin and lightweight—which would make the space suits resistant to damage right from the start.

With thinner materials, those spacesuits would also be much more flexible, making it easier for astronauts to move through the spaceship or planetary environment to explore and perform scientific tasks.

Along with repairing damage to the suits, there are nanotech applications that would monitor and repair the astronaut inside.  Of course, the word “repair” is used a little loosely; what’s referred to would be the medical monitoring and treatment capabilities that nanotech could make available.

Space travel and space exploration are extremely dangerous to humans, no two ways about it, and even the most advanced protective efforts could still fail or be damaged.  This means it’s also vital to be able to monitor astronauts’ health and vitals, as well as be able to administer a variety of treatments effectively and on demand.

 

Artist’s conception of nanorobots that can enter the human body and treat disease or deliver medication at the cellular level.

There is already research into nanotech-based solutions for things like administering drugs and using nanosensors to monitor patient health—and those will become essential to keeping astronauts healthy.  For starters, the aforementioned space suits can have an inner layer that uses nanosensors to monitor various aspects of the astronaut’s vitals, such as temperature, heartbeat, respiration and oxygen levels all the way down to the level of blood glucose and other important factors.

These sensors would be able to relay the data to the astronaut via a heads-up display (HUD) in their space suit, or back to the main base or ship system, ensuring real-time response to any health issues.  Nanosensors could also communicate with nano-implants or other medical devices within the astronaut’s body to deliver drugs, vitamins or emergency medicine as needed, ensuring the astronaut will be in peak condition while performing their tasks.

In an extreme case, such as sustaining an injury through or beneath the suit (like Watney in The Martian), many researchers envision something like a nanogel that will recognize there is an injury and have the ability to self-organize to seal the wound, supply antibiotics, and otherwise provide enough treatment that the astronaut will have time to return to the ship or base to receive proper medical care.

Nanotechnology-Built Habitats

Once the travel, exploration and personal gear are covered, what’s left is where these astronauts will stay once they arrive on a new planet.

Colonization of other planets is a long-standing human dream, and our technological capabilities are finally approaching the sophistication necessary to accomplish this goal—just look at NASA’s Mars 2020 plan.

Habitat construction for planetary colonization will greatly benefit from the use of nanotech in several ways, the most significant of which will be with building structure for humans to work and live.

3D printing is a popular proposal for creating habitat spaces  and is a large-scale example of what sufficiently advanced nanotech could do at the much smaller scale.  Current technologies envision essentially an oversized 3D printer that can “print” a building out of cement-like mixtures mined and processed from surface materials.

Houses designed by Zopherus as part of NASA’s Habitat Centennial Challenge, which would be 3D printed and deposited by the roving lander, pictured at right. (Image courtesy of NASA.)

It’s a good idea, and would certainly do the job; however, a nanotech solution would be much more efficient—such as swarms of tiny nanobots doing the mining and mineral collection, then processing the minerals into a building material compound, then collaborating to deposit the building material according to a programmed habitat design.

Ideally, these nanobots would be programmed ahead of time with instructions for those tasks and the design of the habitat, then they would act collectively and autonomously to complete the project.  This could be much more efficient than a single large printer extruding material to build, and would enable a far greater ability to custom-design habitat buildings for the needs of the astronauts and the environmental factors unique to a given planetary surface.  Transporting the necessary equipment would also be easier, since all a habitat-building mission would need is a lander full of nanobots, rather than trying to launch and land heavy equipment.

However, it’s still possible that the giant 3D printer will be the way to go—at least in the beginning—but that doesn’t mean nanotech won’t still be useful.  Particularly nanomaterials, as the building material being derived from the planet’s surface could still be augmented by nanotech to be stronger, lighter, and more resistant to radiation or toxicity.

Another method of building habitable spaces on a planet is to create tunnels beneath the surface, which would provide some degree of natural protection from radiation or a toxic atmosphere.  Nanotech would be useful in this scenario, as well, with nanobots able to dig the tunnels, and turn these minerals into a strong nanomaterial to then line the tunnel walls and build other structures beneath the surface.

Aside from buildings, extra-terrestrial colonies will also need reliable communication, both with other colonization groups on the planet’s surface and with orbiting communications satellites or space ships.  Just as self-assembling, AI-enabled nanobots would organize themselves into communications equipment and antennas during the planetary exploration phase, they would be able to continue this function for an established colony. 

Potential Dangers

Overall, nanotech and nanorobotics look extremely promising for applications in space exploration and colonization—but a rosy outlook by no means guarantees a problem-free outcome.

Popularized by K. Eric Drexler in his 1986 book Engines of Creation, the “grey goo” scenario—an idea that nano-scale assemblers capable of fabricating any object, as well as self-replicating, could run amok and consume everything in their path—is often what first comes to mind when people consider the ways nanotechnology could go wrong.  But this really is largely science fiction.

The more realistic risks to nanotechnology are similar to the risk factors inherent in any new technology or chemical compound.  For example, while the idea of nanobots used to heal wounds is appealing, there is still no way of knowing just what the effect would be on the human physiology.  Currently there is a trend toward using nanoparticles in consumer products—for example, cosmetics and skin care products—we are also seeing evidence that these nanoparticles can cause skin and organ damage with repeated exposure.  Nanotechnology for healthcare and medical treatment is still in it’s infancy, and as yet there’s no way to know whether there will be long term effects from introducing foreign nanoparticles or nanorobotics into the human body.

There is also the risk of environmental contamination, a particular concern when exploring previously untouched extraterrestrial planetary surfaces.  Current missions to explore the moon, Mars or asteroids far out in the solar system are meticulous about ensuring that no biological contaminants are on the equipment, landers or rovers that will be coming into contact with these distant environments. 

However, many of the nanotechnology solutions to surveying these environments involve releasing nanoscale sensors or robotics into the air and onto the ground. There is a realistic expectation with these swarms that not only would it be virtually impossible to reclaim every last one of them, but the presence of these foreign objects could contaminate or otherwise have an adverse effect on the environment.

Sense

From Wikipedia, the free encyclopedia

 

Five Aristotelian senses and their respective sensory organs inherent among Homo sapiens

An allegory of five senses. Still Life by Pieter Claesz, 1623. The painting illustrates the senses through musical instruments, a compass, a book, food and drink, a mirror, incense and an open perfume bottle. The tortoise may be an illustration of touch or an allusion to the opposite (the tortoise isolating in its shell).

A sense is a physiological capacity of organisms that provides data for perception. The senses and their operation, classification, and theory are overlapping topics studied by a variety of fields, most notably neuroscience, cognitive psychology (or cognitive science), and philosophy of perception. The nervous system has a specific sensory nervous system, and a sense organ, or sensor, dedicated to each sense.

Humans have a multitude of sensors. Sight (vision), hearing (audition), taste (gustation), smell (olfaction), and touch (somatosensation) are the five traditionally recognized senses. The ability to detect other stimuli beyond those governed by these most broadly recognized senses also exists, and these sensory modalities include temperature (thermoception), kinesthetic sense (proprioception), pain (nociception), balance (equilibrioception), vibration (mechanoreception), and various internal stimuli (e.g. the different chemoreceptors for detecting salt and carbon dioxide concentrations in the blood, or sense of hunger and sense of thirst). However, what constitutes a sense is a matter of some debate, leading to difficulties in defining what exactly a distinct sense is, and where the borders between responses to related stimuli lie.

Other animals also have receptors to sense the world around them, with degrees of capability varying greatly between species. Humans have a comparatively weak sense of smell and a stronger sense of sight relative to many other mammals while some animals may lack one or more of the traditional five senses. Some animals may also intake and interpret sensory stimuli in very different ways. Some species of animals are able to sense the world in a way that humans cannot, with some species able to sense electrical and magnetic fields, and detect water pressure and currents.

Definition

Detail of The Senses of Hearing, Touch and Taste, Jan Brueghel the Elder, 1618

A broadly acceptable definition of a sense would be "A system that consists of a group of sensory cell types that responds to a specific physical phenomenon, and that corresponds to a particular group of regions within the brain where the signals are received and interpreted." There is no firm agreement as to the number of senses because of differing definitions of what constitutes a sense.

The senses are frequently divided into exteroceptive and interoceptive:

• Exteroceptive senses are senses that perceive the body's own position, motion, and state, known as proprioceptive senses. External senses include the traditional five: sight, hearing, touch, smell and taste, as well as thermoception (temperature differences) and possibly an additional weak magnetoception (direction). Proprioceptive senses include nociception (pain); equilibrioception (balance); proprioception (a sense of the position and movement of the parts of one's own body).
• Interoceptive senses are senses that perceive sensations in internal organs.

Non-human animals may possess senses that are absent in humans, such as electroreception and detection of polarized light.

In Buddhist philosophy, Ayatana or "sense-base" includes the mind as a sense organ, in addition to the traditional five. This addition to the commonly acknowledged senses may arise from the psychological orientation involved in Buddhist thought and practice. The mind considered by itself is seen as the principal gateway to a different spectrum of phenomena that differ from the physical sense data. This way of viewing the human sense system indicates the importance of internal sources of sensation and perception that complements our experience of the external world.

Five "traditional" senses

Sight

In this painting by Pietro Paolini, each individual represents one of the five senses.

Sight or vision (adjectival form: visual/optical) is the capability of the eye(s) to focus and detect images of visible light on photoreceptors in the retina of each eye that generates electrical nerve impulses for varying colors, hues, and brightness. There are two types of photoreceptors: rods and cones. Rods are very sensitive to light, but do not distinguish colors. Cones distinguish colors, but are less sensitive to dim light. There is some disagreement as to whether this constitutes one, two or three senses. Neuroanatomists generally regard it as two senses, given that different receptors are responsible for the perception of color and brightness. Some argue that stereopsis, the perception of depth using both eyes, also constitutes a sense, but it is generally regarded as a cognitive (that is, post-sensory) function of the visual cortex of the brain where patterns and objects in images are recognized and interpreted based on previously learned information. This is called visual memory.

The inability to see is called blindness. Blindness may result from damage to the eyeball, especially to the retina, damage to the optic nerve that connects each eye to the brain, and/or from stroke (infarcts in the brain). Temporary or permanent blindness can be caused by poisons or medications.

People who are blind from degradation or damage to the visual cortex, but still have functional eyes, are actually capable of some level of vision and reaction to visual stimuli but not a conscious perception; this is known as blindsight. People with blindsight are usually not aware that they are reacting to visual sources, and instead just unconsciously adapt their behaviour to the stimulus.

On February 14, 2013 researchers developed a neural implant that gives rats the ability to sense infrared light which for the first time provides living creatures with new abilities, instead of simply replacing or augmenting existing abilities.

Hearing

Hearing or audition (adjectival form: auditory) is the sense of sound perception. Hearing is all about vibration. Mechanoreceptors turn motion into electrical nerve pulses, which are located in the inner ear. Since sound is vibration, propagating through a medium such as air, the detection of these vibrations, that is the sense of the hearing, is a mechanical sense because these vibrations are mechanically conducted from the eardrum through a series of tiny bones to hair-like fibers in the inner ear, which detect mechanical motion of the fibers within a range of about 20 to 20,000 hertz, with substantial variation between individuals. Hearing at high frequencies declines with an increase in age. Inability to hear is called deafness or hearing impairment. Sound can also be detected as vibrations conducted through the body by tactition. Lower frequencies that can be heard are detected this way. Some deaf people are able to determine direction and location of vibrations picked up through the feet.

Taste

Taste or gustation (adjectival form: gustatory) is one of the traditional five senses. It refers to the capability to detect the taste of substances such as food, certain minerals, and poisons, etc. The sense of taste is often confused with the "sense" of flavor, which is a combination of taste and smell perception.

Philippe Mercier - The Sense of Taste - Google Art Project

Flavor depends on odor, texture, and temperature as well as on taste. Humans receive tastes through sensory organs called taste buds, or gustatory calyculi, concentrated on the upper surface of the tongue. There are five basic tastes: sweet, bitter, sour, salty and umami. Other tastes such as calcium and free fatty acids may also be basic tastes but have yet to receive widespread acceptance. The inability to taste is called ageusia.

Smell

Smell or olfaction (adjectival form: olfactory) is the other "chemical" sense. Unlike taste, there are hundreds of olfactory receptors (388 according to one source), each binding to a particular molecular feature. Odor molecules possess a variety of features and, thus, excite specific receptors more or less strongly. This combination of excitatory signals from different receptors makes up what we perceive as the molecule's smell.

The sense of smell Philippe Mercier

In the brain, olfaction is processed by the olfactory system. Olfactory receptor neurons in the nose differ from most other neurons in that they die and regenerate on a regular basis. The inability to smell is called anosmia. Some neurons in the nose are specialized to detect pheromones.

Touch

Touch or somatosensation (adjectival form: somatic), also called tactition (adjectival form: tactile) or mechanoreception, is a perception resulting from activation of neural receptors, generally in the skin including hair follicles, but also in the tongue, throat, and mucosa. A variety of pressure receptors respond to variations in pressure (firm, brushing, sustained, etc.). The touch sense of itching caused by insect bites or allergies involves special itch-specific neurons in the skin and spinal cord. The loss or impairment of the ability to feel anything touched is called tactile anesthesia. Paresthesia is a sensation of tingling, pricking, or numbness of the skin that may result from nerve damage and may be permanent or temporary.

Other senses

Balance and acceleration

Balance, equilibrioception, or vestibular sense is the sense that allows an organism to sense body movement, direction, and acceleration, and to attain and maintain postural equilibrium and balance. The organ of equilibrioception is the vestibular labyrinthine system found in both of the inner ears. In technical terms, this organ is responsible for two senses of angular momentum acceleration and linear acceleration (which also senses gravity), but they are known together as equilibrioception.

The vestibular nerve conducts information from sensory receptors in three ampulla that sense motion of fluid in three semicircular canals caused by three-dimensional rotation of the head. The vestibular nerve also conducts information from the utricle and the saccule, which contain hair-like sensory receptors that bend under the weight of otoliths (which are small crystals of calcium carbonate) that provide the inertia needed to detect head rotation, linear acceleration, and the direction of gravitational force.

Temperature

Thermoception is the sense of heat and the absence of heat (cold) by the skin and internal skin passages, or, rather, the heat flux (the rate of heat flow) in these areas. There are specialized receptors for cold (declining temperature) and for heat (increasing temperature). The cold receptors play an important part in the animal's sense of smell, telling wind direction. The heat receptors are sensitive to infrared radiation and can occur in specialized organs, for instance in pit vipers. The thermoceptors in the skin are quite different from the homeostatic thermoceptors in the brain (hypothalamus), which provide feedback on internal body temperature.

Proprioception

Proprioception, the kinesthetic sense, provides the parietal cortex of the brain with information on the movement and relative positions of the parts of the body. Neurologists test this sense by telling patients to close their eyes and touch their own nose with the tip of a finger. Assuming proper proprioceptive function, at no time will the person lose awareness of where the hand actually is, even though it is not being detected by any of the other senses. Proprioception and touch are related in subtle ways, and their impairment results in surprising and deep deficits in perception and action.

Pain

Nociception (physiological pain) signals nerve-damage or damage to tissue. The three types of pain receptors are cutaneous (skin), somatic (joints and bones), and visceral (body organs). It was previously believed that pain was simply the overloading of pressure receptors, but research in the first half of the 20th century indicated that pain is a distinct phenomenon that intertwines with all of the other senses, including touch. Pain was once considered an entirely subjective experience, but recent studies show that pain is registered in the anterior cingulate gyrus of the brain. The main function of pain is to attract our attention to dangers and motivate us to avoid them. For example, humans avoid touching a sharp needle, or hot object, or extending an arm beyond a safe limit because it is dangerous, and thus hurts. Without pain, people could do many dangerous things without being aware of the dangers.

Sexual stimulation

Sexual stimulation is any stimulus (including bodily contact) that leads to, enhances and maintains sexual arousal, and may lead to orgasm. Distinct from the general sense of touch, sexual stimulation is strongly tied to hormonal activity and chemical triggers in the body. Although sexual arousal may arise without physical stimulation, achieving orgasm usually requires physical sexual stimulation (stimulation of the Krause-Finger corpuscles found in erogenous zones of the body).

Other internal senses

An internal sense also known as interoception is "any sense that is normally stimulated from within the body". These involve numerous sensory receptors in internal organs, such as stretch receptors that are neurologically linked to the brain. Interoception is thought to be atypical in clinical conditions such as alexithymia. Some examples of specific receptors are:

• Hunger is a sensation that is governed by a set of brain structures (e.g., the hypothalamus) that are responsible for energy homeostasis.
• Pulmonary stretch receptors are found in the lungs and control the respiratory rate.
• Peripheral chemoreceptors in the brain monitor the carbon dioxide and oxygen levels in the brain to give a feeling of suffocation if carbon dioxide levels get too high.
• The chemoreceptor trigger zone is an area of the medulla in the brain that receives inputs from blood-borne drugs or hormones, and communicates with the vomiting center.
• Chemoreceptors in the circulatory system also measure salt levels and prompt thirst if they get too high; they can also respond to high blood sugar levels in diabetics.
• Cutaneous receptors in the skin not only respond to touch, pressure, temperature and vibration, but also respond to vasodilation in the skin such as blushing.
• Stretch receptors in the gastrointestinal tract sense gas distension that may result in colic pain.
• Stimulation of sensory receptors in the esophagus result in sensations felt in the throat when swallowing, vomiting, or during acid reflux.
• Sensory receptors in pharynx mucosa, similar to touch receptors in the skin, sense foreign objects such as food that may result in a gag reflex and corresponding gagging sensation.
• Stimulation of sensory receptors in the urinary bladder and rectum may result in sensations of fullness.
• Stimulation of stretch sensors that sense dilation of various blood vessels may result in pain, for example headache caused by vasodilation of brain arteries.
• Cardioception refers to the perception of the activity of the heart.
• Opsins and direct DNA damage in melanocytes and keratinocytes can sense ultraviolet radiation, which plays a role in pigmentation and sunburn.

Perception not based on a specific sensory organ

Time

Chronoception refers to how the passage of time is perceived and experienced. Although the sense of time is not associated with a specific sensory system, the work of psychologists and neuroscientists indicates that human brains do have a system governing the perception of time, composed of 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-range (ultradian) timekeeping.

One or more dopaminergic pathways in the central nervous system appear to have a strong modulatory influence on mental chronometry, particularly interval timing.

Agency

The sense of agency refers to the subjective feeling of having chosen a particular action. Some conditions, such as schizophrenia, can lead to a loss of this sense, causing a person to feel like a machine or even leading to delusions of being controlled from some outside source. The opposite extreme occurs too, with some people experiencing everything in their environment as if they had decided that it would happen.

Even in non-pathological cases, there is a measurable difference between making a decision and the feeling of agency. Through methods such as the Libet experiment, a gap of half a second or more can be detected from the time when there are detectable neurological signs of a decision having been made to the time when the subject actually becomes conscious of the decision.

There are also experiments in which an illusion of agency is induced in psychologically normal subjects. In Wegner and Wheatley 1999, subjects were given instructions to move a mouse around a scene and point to an image about once every thirty seconds. However, a second person—acting as a test subject but actually a confederate—had their hand on the mouse at the same time, and controlled some of the movement. Experimenters were able to arrange for subjects to perceive certain "forced stops" as if they were their own choice.

Familiarity

Recognition memory is sometimes divided into two functions by neuroscientists: familiarity and recollection. A strong sense of familiarity can occur without any recollection, for example in cases of deja vu. The temporal lobe, in particular the perirhinal cortex, responds differently to stimuli which feel novel than to things which feel familiar. Firing rates in the perirhinal cortex are connected with the sense of familiarity in humans and other mammals. In tests, stimulating this area at 10–15 Hz caused animals to treat even novel images as familiar, and stimulation at 30–40 Hz caused novel images to be partially treated as familiar. Specifically, stimulation at 30–40 Hz led to animals looking at a familiar image for longer periods, as they would for an unfamiliar one; but it did not lead to the same exploration behavior normally associated with novelty. Recent studies on lesions in the area concluded that rats with a damaged perirhinal cortex were still more interested in exploring when novel objects were present, but seemed unable to tell novel objects from familiar ones—they examined both equally. Thus, other brain regions are involved with noticing unfamiliarity, but the perirhinal cortex is needed to associate the feeling with a specific source.

Non-human senses

Analogous to human senses

Other living organisms have receptors to sense the world around them, including many of the senses listed above for humans. However, the mechanisms and capabilities vary widely.

Smell

Most non-human mammals have a much keener sense of smell than humans, although the mechanism is similar. An example of smell in non-mammals is that of sharks, which combine their keen sense of smell with timing to determine the direction of a smell. They follow the nostril that first detected the smell. Insects have olfactory receptors on their antennae.

Vomeronasal organ

Many animals (salamanders, reptiles, mammals) have a vomeronasal organ that is connected with the mouth cavity. In mammals it is mainly used to detect pheromones of marked territory, trails, and sexual state. Reptiles like snakes and monitor lizards make extensive use of it as a smelling organ by transferring scent molecules to the vomeronasal organ with the tips of the forked tongue. In reptiles the vomeronasal organ is commonly referred to as Jacobsons organ. In mammals, it is often associated with a special behavior called flehmen characterized by uplifting of the lips. The organ is vestigial in humans, because associated neurons have not been found that give any sensory input in humans.

Taste

Flies and butterflies have taste organs on their feet, allowing them to taste anything they land on.

Catfish have taste organs across their entire bodies, and can taste anything they touch, including chemicals in the water.

Vision and light sensing

Cats have the ability to see in low light, which is due to muscles surrounding their irides–which contract and expand their pupils–as well as to the tapetum lucidum, a reflective membrane that optimizes the image. Pit vipers, pythons and some boas have organs that allow them to detect infrared light, such that these snakes are able to sense the body heat of their prey. The common vampire bat may also have an infrared sensor on its nose. It has been found that birds and some other animals are tetrachromats and have the ability to see in the ultraviolet down to 300 nanometers. Bees and dragonflies are also able to see in the ultraviolet. Mantis shrimps can perceive both polarized light and multispectral images and have twelve distinct kinds of color receptors, unlike humans which have three kinds and most mammals which have two kinds.

Cephalopods have the ability to change color using chromatophores in their skin. Researchers believe that opsins in the skin can sense different wavelengths of light and help the creatures choose a coloration that camouflages them, in addition to light input from the eyes. Other researchers hypothesize that cephalopod eyes in species which only have a single photoreceptor protein may use chromatic aberration to turn monochromatic vision into color vision, explaining pupils shaped like the letter U, the letter W, or a dumbbell, as well as explaining the need for colorful mating displays. Some cephalopods can distinguish the polarization of light.

Balance

Many invertebrates have a statocyst, which is a sensor for acceleration and orientation that works very differently from the mammalian's semi-circular canals.

Sensing gravity

Some plants (such as mustard) have genes that are necessary for the plant to sense the direction of gravity. If these genes are disabled by a mutation, a plant cannot grow upright.

Not analogous to human senses

In addition, some animals have senses that humans do not, including the following:

Echolocation

Certain animals, including bats and cetaceans, have the ability to determine orientation to other objects through interpretation of reflected sound (like sonar). They most often use this to navigate through poor lighting conditions or to identify and track prey. There is currently an uncertainty whether this is simply an extremely developed post-sensory interpretation of auditory perceptions or it actually constitutes a separate sense. Resolution of the issue will require brain scans of animals while they actually perform echolocation, a task that has proven difficult in practice.
Blind people report they are able to navigate and in some cases identify an object by interpreting reflected sounds (especially their own footsteps), a phenomenon known as human echolocation.

Electroreception

Electroreception (or electroception) is the ability to detect electric fields. Several species of fish, sharks, and rays have the capacity to sense changes in electric fields in their immediate vicinity. For cartilaginous fish this occurs through a specialized organ called the Ampullae of Lorenzini. Some fish passively sense changing nearby electric fields; some generate their own weak electric fields, and sense the pattern of field potentials over their body surface; and some use these electric field generating and sensing capacities for social communication. The mechanisms by which electroceptive fish construct a spatial representation from very small differences in field potentials involve comparisons of spike latencies from different parts of the fish's body.

The only orders of mammals that are known to demonstrate electroception are the dolphin and monotreme orders. Among these mammals, the platypus has the most acute sense of electroception.

A dolphin can detect electric fields in water using electroreceptors in vibrissal crypts arrayed in pairs on its snout and which evolved from whisker motion sensors. These electroreceptors can detect electric fields as weak as 4.6 microvolts per centimeter, such as those generated by contracting muscles and pumping gills of potential prey. This permits the dolphin to locate prey from the seafloor where sediment limits visibility and echolocation.

Body modification enthusiasts have experimented with magnetic implants to attempt to replicate this sense. However, in general humans (and it is presumed other mammals) can detect electric fields only indirectly by detecting the effect they have on hairs. An electrically charged balloon, for instance, will exert a force on human arm hairs, which can be felt through tactition and identified as coming from a static charge (and not from wind or the like). This is not electroreception, as it is a post-sensory cognitive action.

Magnetoception

Magnetoception (or magnetoreception) is the ability to detect the direction one is facing based on the Earth's magnetic field. Directional awareness is most commonly observed in birds, which rely on their magnetic sense to navigate during migration. It has also been observed in insects such as bees. Cattle make use of magnetoception to align themselves in a north-south direction. Magnetotactic bacteria build miniature magnets inside themselves and use them to determine their orientation relative to the Earth's magnetic field.

Hygroreception

Hygroreception is the ability to detect changes in the moisture content of the environment.

Infrared sensing

The ability to sense infrared thermal radiation evolved independently in various families of snakes. Essentially, it allows these reptiles to "see" radiant heat at wavelengths between 5 and 30 μm to a degree of accuracy such that a blind rattlesnake can target vulnerable body parts of the prey at which it strikes. It was previously thought that the organs evolved primarily as prey detectors, but it is now believed that it may also be used in thermoregulatory decision making. The facial pit underwent parallel evolution in pitvipers and some boas and pythons, having evolved once in pitvipers and multiple times in boas and pythons. The electrophysiology of the structure is similar between the two lineages, but they differ in gross structural anatomy. Most superficially, pitvipers possess one large pit organ on either side of the head, between the eye and the nostril (Loreal pit), while boas and pythons have three or more comparatively smaller pits lining the upper and sometimes the lower lip, in or between the scales. Those of the pitvipers are the more advanced, having a suspended sensory membrane as opposed to a simple pit structure. Within the family Viperidae, the pit organ is seen only in the subfamily Crotalinae: the pitvipers. The organ is used extensively to detect and target endothermic prey such as rodents and birds, and it was previously assumed that the organ evolved specifically for that purpose. However, recent evidence shows that the pit organ may also be used for thermoregulation. According to Krochmal et al., pitvipers can use their pits for thermoregulatory decision making while true vipers (vipers who do not contain heat-sensing pits) cannot.

In spite of its detection of IR light, the pits' IR detection mechanism is not similar to photoreceptors – while photoreceptors detect light via photochemical reactions, the protein in the pits of snakes is in fact a temperature sensitive ion channel. It senses infrared signals through a mechanism involving warming of the pit organ, rather than chemical reaction to light. This is consistent with the thin pit membrane, which allows incoming IR radiation to quickly and precisely warm a given ion channel and trigger a nerve impulse, as well as vascularize the pit membrane in order to rapidly cool the ion channel back to its original "resting" or "inactive" temperature.

Other

• Pressure detection uses the organ of Weber, a system consisting of three appendages of vertebrae transferring changes in shape of the gas bladder to the middle ear. It can be used to regulate the buoyancy of the fish. Fish like the weather fish and other loaches are also known to respond to low pressure areas but they lack a swim bladder.
• Current detection is a detection system of water currents, consisting mostly of vortices, found in the lateral line of fish and aquatic forms of amphibians. The lateral line is also sensitive to low-frequency vibrations. The mechanoreceptors are hair cells, the same mechanoreceptors for vestibular sense and hearing. It is used primarily for navigation, hunting, and schooling. The receptors of the electrical sense are modified hair cells of the lateral line system.
• Polarized light direction/detection is used by bees to orient themselves, especially on cloudy days. Cuttlefish can also perceive the polarization of light. Most sighted humans can in fact learn to roughly detect large areas of polarization by an effect called Haidinger's brush, however this is considered an entoptic phenomenon rather than a separate sense.
• Slit sensillae of spiders detect mechanical strain in the exoskeleton, providing information on force and vibrations.

Plant senses

By using a variety of sense receptors, plants sense light, gravity, temperature, humidity, chemical substances, chemical gradients, reorientation, magnetic fields, infections, tissue damage and mechanical pressure. The absence of a nervous system notwithstanding, plants interpret and respond to these stimuli by a variety of hormonal and cell-to-cell communication pathways that result in movement, morphological changes and physiological state alterations at the organism level, that is, result in plant behavior. Such physiological and cognitive functions are generally not believed to give rise to mental phenomena or qualia, however, as these are typically considered the product of nervous system activity. The emergence of mental phenomena from the activity of systems functionally or computationally analogous to that of nervous systems is, however, a hypothetical possibility explored by some schools of thought in the philosophy of mind field, such as functionalism and computationalism.

Culture

Lairesse's Allegory of the Five Senses

In the time of William Shakespeare, there were commonly reckoned to be five wits or five senses. At that time, the words "sense" and "wit" were synonyms, so the senses were known as the five outward wits. This traditional concept of five senses is common today.

The traditional five senses are enumerated as the "five material faculties" (pañcannaṃ indriyānaṃ avakanti) in Hindu literature. They appear in allegorical representation as early as in the Katha Upanishad (roughly 6th century BC), as five horses drawing the "chariot" of the body, guided by the mind as "chariot driver".

Depictions of the five traditional senses as allegory became a popular subject for seventeenth-century artists, especially among Dutch and Flemish Baroque painters. A typical example is Gérard de Lairesse's Allegory of the Five Senses (1668), in which each of the figures in the main group alludes to a sense: Sight is the reclining boy with a convex mirror, hearing is the cupid-like boy with a triangle, smell is represented by the girl with flowers, taste is represented by the woman with the fruit, and touch is represented by the woman holding the bird.