Intellectual giftedness

From Wikipedia, the free encyclopedia

Intellectual giftedness is an intellectual ability significantly higher than average. It is a characteristic of children, variously defined, that motivates differences in school programming. It is thought to persist as a trait into adult life, with various consequences studied in longitudinal studies of giftedness over the last century. There is no generally agreed definition of giftedness for either children or adults, but most school placement decisions and most longitudinal studies over the course of individual lives have followed people with IQs in the top two percent of the population – that is, IQs above 130. Definitions of giftedness also vary across cultures.

The various definitions of intellectual giftedness include either general high ability or specific abilities. For example, by some definitions an intellectually gifted person may have a striking talent for mathematics without equally strong language skills. In particular, the relationship between artistic ability or musical ability and the high academic ability usually associated with high IQ scores is still being explored, with some authors referring to all of those forms of high ability as "giftedness", while other authors distinguish "giftedness" from "talent". There is still much controversy and much research on the topic of how adult performance unfolds from trait differences in childhood, and what educational and other supports best help the development of adult giftedness.

Identification

Overview

The identification of giftedness first emerged after the development of IQ tests for school placement. It has since become an important issue for schools, as the instruction of gifted students often presents special challenges. During the twentieth century, gifted children were often classified via IQ tests; other identification procedures have been proposed but are only used in a minority of cases in most public schools in the English-speaking world. Developing useful identification procedures for students who could benefit from a more challenging school curriculum is an ongoing problem in school administration.

Because of the key role that gifted education programs in schools play in the identification of gifted individuals, both children and adults, it is worthwhile to examine how schools define the term "gifted".

Definitions

For many years, psychometricians and psychologists, following in the footsteps of Lewis Terman in 1916, equated giftedness with high IQ. This "legacy" survives to the present day, in that giftedness and high IQ continue to be equated in some conceptions of giftedness. Since that early time, however, other researchers (e.g., Raymond Cattell, J. P. Guilford, and Louis Leon Thurstone) have argued that intellect cannot be expressed in such a unitary manner, and have suggested more multifaceted approaches to intelligence.

Research conducted in the 1980s and 1990s has provided data which support notions of multiple components to intelligence. This is particularly evident in the reexamination of "giftedness" by Sternberg and Davidson in their collection of articles Conceptions of Giftedness (1986; second edition 2005). The many different conceptions of giftedness presented, although distinct, are interrelated in several ways. Most of the investigators define giftedness in terms of multiple qualities, not all of which are intellectual. IQ scores are often viewed as inadequate measures of giftedness. Motivation, high self-concept, and creativity are key qualities in many of these broadened conceptions of giftedness.

Joseph Renzulli's (1978) "three ring" definition of giftedness is one frequently mentioned conceptualization of giftedness. Renzulli's definition, which defines gifted behaviors rather than gifted individuals, is composed of three components as follows: Gifted behavior consists of behaviors that reflect an interaction among three basic clusters of human traits—above average ability, high levels of task commitment, and high levels of creativity. Individuals capable of developing gifted behavior are those possessing or capable of developing this composite set of traits and applying them to any potentially valuable area of human performance. Persons who manifest or are capable of developing an interaction among the three clusters require a wide variety of educational opportunities and services that are not ordinarily provided through regular instructional programs.

In Identifying Gifted Children: A Practical Guide, Susan K. Johnsen explains that gifted children all exhibit the potential for high performance in the areas included in the United States' federal definition of gifted and talented students:

There is a federal government statutory definition of gifted and talented students in the United States.

The term "gifted and talented" when used in respect to students, children, or youth means students, children, or youth who give evidence of high performance capability in areas such as intellectual, creative, artistic, or leadership capacity, or in specific academic fields, and who require services or activities not ordinarily provided by the school in order to fully develop such capabilities." (P.L. 103–382, Title XIV, p. 388)

This definition has been adopted partially or completely by the majority of the individual states in the United States (which have the main responsibility for education policy as compared to the federal government). Most states have a definition similar to that used in the State of Texas:

"gifted and talented student" means a child or youth who performs at or shows the potential for performing at a remarkably high level of accomplishment when compared to others of the same age, experience, or environment, and who

• exhibits high performance capability in an intellectual, creative, or artistic area;
• possesses an unusual capacity for leadership; or
• excels in a specific academic field." (74th legislature of the State of Texas, Chapter 29, Subchapter D, Section 29.121)

The major characteristics of these definitions are (a) the diversity of areas in which performance may be exhibited (e.g., intellectual, creativity, artistic, leadership, academically), (b) the comparison with other groups (e.g., those in general education classrooms or of the same age, experience, or environment), and (c) the use of terms that imply a need for development of the gift (e.g., capability and potential).

Since the late 90s, the development of the brain of people with high IQ scores has been shown to be different than the development of the brain of people with an average IQ scores. A longitudinal study over 6 years has shown that high-IQ children have a thinner cerebral cortex when young, which then grows quickly and becomes significantly thicker than the other children's by the time they became teenagers.

Identification methods

Many schools use a variety of assessments of students' capability and potential when identifying gifted children. These may include portfolios of student work, classroom observations, achievement tests, and IQ test scores. Most educational professionals accept that no single criterion can be used in isolation to accurately identify a gifted child.

One of the criteria used in identification may be an IQ test score. Until the late 1960s, when “giftedness” was defined by an IQ score, a school district simply set an arbitrary score (usually in the 130 range) and a student either did or did not “make the cut”. It is no longer accepted today in academic circles; however, it's still used by many school districts because it is simple and not entirely without merit. Although a high IQ score is not the sole indicator of giftedness, usually if a student has a very high IQ, that is a significant indicator of high academic potential. Because of this consideration, if a student scores highly on an IQ test, but performs at an average or below average level academically, school officials may think that this issue warrants further investigation as an example of underachievement. However, scholars of educational testing point out that a test-taker's scores on any two tests may vary, so a lower score on an achievement test than on an IQ test neither necessarily indicates that the test-taker is underachieving nor necessarily that the school curriculum is underchallenging.

IQ classification varies from one publisher to another. IQ tests do not have validity for determining test-takers' rank order at higher IQ levels, and are perhaps only effective at determining whether a student is gifted rather than distinguishing among levels of giftedness. The Wechsler tests have a standard score ceiling of 160. Today, the Wechsler child and adult IQ tests are by far the most commonly used IQ tests in hospitals, schools, and private psychological practice. Older versions of the Stanford-Binet test, now obsolete, and the Cattell IQ test purport to yield IQ scores of 180 or higher, but those scores are not comparable to scores on currently normed tests. The Stanford-Binet Third Revision (Form L-M) yields consistently higher numerical scores for the same test-taker than scores obtained on current tests. This has prompted some authors on identification of gifted children to promote the Stanford-Binet form L-M, which has long been obsolete, as the only test with a sufficient ceiling to identify the exceptionally and profoundly gifted, despite the Stanford-Binet L-M never having been normed on a representative national sample. Because the instrument is outdated, current results derived from the Stanford-Binet L-M generate inflated and inaccurate scores. The IQ assessment of younger children remains debated.

While many people believe giftedness is a strictly quantitative difference, measurable by IQ tests, some authors on the "experience of being" have described giftedness as a fundamentally different way of perceiving the world, which in turn affects every experience had by the gifted individual. This view is doubted by some scholars who have closely studied gifted children longitudinally.

Across cultures

Characteristics and attributes associated with giftedness varies across cultures. While intelligence is extremely important in Western and some other cultures, such an emphasis is not consistent throughout the world. For example, in Japan, there is more of a value placed on an individual's motivation and diligence. When Japanese students are given a task, they attribute success to factors like effort, whereas American students tend to attribute success to ability. Similarly, when Japanese students fail, they refer the failure to lack of effort. On the other hand, American students believe failure is due to a lack of ability. There are conceptions in Rural Kenya that identify four types of intelligence: initiative (paro), knowledge and skills (rieko), respect (luoro), and comprehension of how to handle real life problems (winjo). Chan cites the Chinese belief that aspects of giftedness are innate, but that people can become gifted through industriousness, perseverance, and learning. Not all who are intellectually gifted display every characteristic that is seen.

There are many reasons gifted students who have various backgrounds are not as successful at Western intelligence/achievement tests:

• Not used to answering questions just for the purpose of showing knowledge – they must use their knowledge to respond to authentic problems.
• May perform poorly on paper-and-pencil tasks in an artificial lab setting.
• May perform poorly on a culturally biased test, especially if not their own.
• Have test anxiety or suffer from stereotype threat.

Many traits that demonstrate intellectual giftedness are identified across a multitude of cultures, such as:

• Displaying advanced reasoning and creative thinking, generating ideas beyond the norm
• Resourceful and adaptable
• Strongly motivated to understand the world
• Well developed vocabulary in native language
• Learns concepts quickly, and builds/develops these concepts
• Strong sense of justice and morality
• Displays leadership skills in various ways, such as persuasion, taking initiative, and leading by example
• Comprehending and using humor beyond their age

Developmental theory

Gifted children may develop asynchronously: their minds are often ahead of their physical growth, and specific cognitive and emotional functions are often developed differently (or to differing extents) at different stages of development. One frequently cited example of asynchronicity in early cognitive development is Albert Einstein, who did not speak until the age of four, but whose later fluency and accomplishments belied this initial delay. Psychologist and cognitive scientist Steven Pinker theorized that, rather than viewing Einstein's (and other famously gifted late-talking individuals) adult accomplishments as existing distinct from, or in spite of, his early language deficits, and rather than viewing Einstein's lingual delay itself as a "disorder", it may be that Einstein's genius and his delay in speaking were developmentally intrinsic to one another.

It has been said that gifted children may advance more quickly through stages established by post-Freudian developmentalists such as Jean Piaget. Gifted individuals also experience the world differently, resulting in certain social and emotional issues.

Francoy Gagne's (2000) Differentiated Model of Giftedness and Talent (DMGT) is a developmental theory that distinguishes giftedness from talent, offering explanation on how outstanding natural abilities (gifts) develop into specific expert skills (talents). According to DMGT theory, "one cannot become talented without first being gifted, or almost so". There are six components that can interact in countless and unique ways that foster the process of moving from having natural abilities (giftedness) to systematically developed skills.

These components consist of the gift (G) itself, chance (C), environmental catalyst (EC), intrapersonal catalyst (IC), learning/practice (LP) and the outcome of talent (T). It is important to know that (C), (IC), and (EC) can facilitate but can also hinder the learning and training of becoming talented. The learning/practice is the moderator. It is through the interactions, both environmental and intrapersonal that influence the process of learning and practice along with/without chance that natural abilities are transformed into talents.

Multiple intelligences theory

Multiple intelligences has been associated with giftedness or overachievement of some developmental areas (Colangelo, 2003). Multiple intelligences has been described as an attitude towards learning, instead of techniques or strategies (Cason, 2001).

Howard Gardner proposed in Frames of Mind (Gardner 1983/1994) that intellectual giftedness may be present in areas other than the typical intellectual realm. The concept of multiple intelligences (MI) makes the field aware of additional potential strengths and proposes a variety of curricular methods. Gardner argued that there are eight intelligences, or different areas in which people assimilate or learn about the world around them: interpersonal, intrapersonal, bodily-kinesthetic, linguistic, logical-mathematical, musical, naturalistic, and spatial-visual.

The most common criticism of Gardner's MI theory is "the belief by scholars that each of the seven multiple intelligences is in fact a cognitive style rather than a stand-alone construct". Others consider the theory not to be sufficiently empirical. This perspective has also been criticized on the grounds that it is ad hoc: that Gardner is not expanding the definition of the word "intelligence", but rather denies the existence of intelligence as traditionally understood, and instead uses the word "intelligence" where other people have traditionally used words like "ability" and "aptitude".

Identification of gifted students with MI is a challenge since there is no simple test to give to determine giftedness of MI. Assessing by observation is potentially most accurate, but potentially highly subjective. MI theory can be applied to not only gifted students, but it can be a lens through which all students can be assessed. This more global perspective may lead to more child-centered instruction and meet the needs of a greater number of children (Colangelo, 2003).

Characteristics

Generally, gifted or advanced students learn more quickly, deeply, and broadly than their peers. They may learn to read early and progress at the same level as normal children who are significantly older. Gifted students also tend to demonstrate high reasoning ability, creativity, curiosity, a large vocabulary, and an excellent memory. They can often master concepts with few repetitions. They may also be perfectionistic, and frequently question authority. Some have trouble relating to or communicating with their peers because of disparities in vocabulary size (especially in the early years), personality, interests, and motivation. As children, they may prefer the company of older children or adults.

Giftedness is frequently not evenly distributed throughout all intellectual spheres. One gifted student may excel in solving logic problems yet be a poor speller. Another may be able to read and write at a far above-average level yet have trouble with mathematics.

It is possible that there are different types of giftedness with their own unique features, just as there are different types of developmental delay.

Giftedness may become noticeable in individuals at different points of development. While early development (i.e. speaking or reading at a very young age) usually comes with giftedness, it is not a determinant of giftedness.

Savantism

Savants are individuals who perform exceptionally in a single field of learning. More often savant and savantism describes people with a single field of learning well beyond what is considered normal, even among the gifted community. Autistic savantism refers to the exceptional abilities occasionally exhibited by people with autism or other pervasive developmental disorders. The term was introduced in a 1978 article in Psychology Today describing this condition.

Gifted minority students in the United States

While White students represent the majority of students enrolled in gifted programs, Black and Hispanic students constitute a percentage less than their enrollment in school. For example, statistics from 1993 indicate that in the U.S., Black students represented 16.2% of public school students, but only constituted 8.4% of students enrolled in gifted education programs. Similarly, while Hispanic students represented 9% of public school students, these students only represented 4.7% of those identified as gifted. However, Asian students make up only 3.6% of the student body, yet constitute 14% in the gifted programs.

In their 2004 study, “Addressing the Achievement Gap Between Minority and Nonminority Children by Increasing Access to Gifted Programs” Olszewski-Kubilius et al. write that minority students are “less likely to be nominated by teachers as potential candidates for gifted programs and, if nominated, are less likely to be selected for the program, particularly when such traditional measures as I.Q. and achievement tests are used for identification.”

This underrepresentation of such students in gifted programs is attributed to a multiplicity of factors including cultural bias of testing procedures, population differences in IQ, selective referrals and educator bias, and a reliance on deficit-based paradigms. To address the inequities in assessment procedures, researchers suggest the use of multiple tests and alternative methods of testing, such as performance-based assessment measures, oral-expressiveness measures as well as non-verbal ability assessments (such as Naglieri Nonverbal Abilities Tests (NNAT) or Raven’s Matrix Analogies Tests).

According to 2013-2014 data collected by the Office of Civil Rights of the Department of Education, White students have more opportunities and exposure to attending schools that offer gifted and talented education programs (GATE) than racial and ethnic minority students, specifically Black and Latino students. Data collected by the Office of Civil Rights department of the Department of Education also reveal that racial/ethnic minority students are underrepresented in gifted and talented education programs. Forty-nine percent of all students enrolled in schools that offer GATE programs are White. Whereas 42% of all students enrolled in schools that offer GATE programs are Latino and Black. Thus revealing that white people have more opportunities to being a part of a school that offers GATE programs. The issue is within these GATE programs 29% of the students are Latino and Black and 57% are White (U.S. Department of Education, 2016). These proportions of student representation are as expected based on differences in population-level IQ scores.

Weinstein’s (2002) suggests that some teachers recommend racial minority students – with the exception to Asian students – to special education and remedial classes more often than gifted and talented classes due to teacher expectancy biases placed on racial minority students. Teachers expectations of their students’ academic performance influences how students perceive themselves. If a teacher expects more success academically from specific students, those students are prone to displaying behavior and work ethic that will set them apart from others in a positive light. Whereas if a teacher only expects bare minimum from his or her students, those students will merely do what is expected of them (Weinstein, 2002).

Racial minority students who are perceived as being disadvantaged from their peers in regards to socioeconomic status tend to have less supportive relations with their teachers (Fitzpatrick, 2015). Due to this lack of support, teachers do not expect these disadvantaged students to go above and beyond, therefore they are often overlooked when it’s time for gifted and talented education program nominations. Research suggests that teacher expectancy bias can also be diminish by matching the racial demographics of students to that of teachers. Gershenson and colleagues (2016) found that non-Black teachers held low expectations of their black students specifically in relation to black male students and math. Whereas, Black teachers held high expectations to black male students in regards to math. This finding suggests that racial diversity in our educators is positive step toward diminishing teacher expectancy bias.

Weinstein and colleagues (1991) aimed to change the low expectations attached to racial minority students of an urban high school that placed many Black and Latino students in remedial programs rather than college preparatory or honor classes. The study aimed to prepare these racial minority students for college level academic work while attending high school. With positive teacher attitudes toward students and greater teacher self-efficacy, the students who were once on track to being recommended for remedial classes where performing at advanced academic levels after 2 years of intervention. They were also more heavily involved in leadership roles at their high school. This study supports the claim that teacher expectancy contributes to how a student sees him or herself in regards to achievements (Weinstein et al., 1991).

Gifted students of color experience success when multicultural content is incorporated in the curriculum and furthermore when the curriculum itself is designed to be culturally and linguistically compatible. A culturally diverse curriculum and instruction encourages gifted minority students to experience a sense of belonging and validation as scholars. Furthermore, the educator's role in this process is significant as Lee et al. argue that "[t]eacher awareness and understanding of students' racial and cultural differences and their ability to incorporate multicultural perspectives into curricular content and instructional techniques may counter gifted minority students' discomfort in being one of the few minority students in gifted programs.”

Twice-exceptional

The term twice-exceptional was coined by James J. Gallagher to denote students who are both gifted and have disabilities. In other words, twice-exceptional students are those who have two special needs. For instance, they might have gifted learning needs and a learning disability, such as attention deficit disorder. Or, they may be a gifted learner and have a developmental disability, such as autism spectrum disorder.

People have known about twice-exceptional students for thirty years; however, identification and program strategies remain ambiguous. These students represent a unique challenge for the educational system. Teachers and educators will need to make special accommodations for their learning deficits (such as remediation), yet adapt the curriculum to meet their advanced learning needs (for instance, through acceleration or enrichment). Twice-exceptional students are considered to be at risk because they are hidden within the general population of their educational environment, and often viewed as either underachievers or average learners.

Early identification and intervention is critical; however, giftedness in the twice-exceptional population is often identified later than in the average population as it is masked by the disability. The disabilities may include auditory processing weaknesses, sensory motor integration issues, visual perceptual difficulties, spatial disorientation, dyslexia, and attention deficits. Recognition of learning difficulties among the gifted is made extremely difficult by virtue of their ability to compensate. Among the signs that the student may be twice-exceptional are apparent inconsistencies between abilities and results, deficits in short-term memory and attention, and negative behaviors such as being sarcastic, negative, or aggressive.

A Child prodigy that demonstrates qualities to be twice-exceptional may encounter additional difficulties. With insight at a young age, it is possible for them to be constantly aware of the risk of failure. This can be detrimental to their emotional state and academic achievement. If a child comprehends a subject well, but due to a developmental disorder receives poor grades in a subject, the child may have difficulty understanding why there is little success in that subject.

Social and emotional issues

Isolation

Social isolation is a common trait in gifted individuals, especially those with no social network of gifted peers. In order to gain popularity, gifted children will often try to hide their abilities to win social approval. Strategies include underachievement (discussed below) and the use of less sophisticated vocabulary when among same-age peers than when among family members or other trusted individuals.

Some believe that the isolation experienced by gifted individuals is not caused by giftedness itself, but by society's response to giftedness and to the rarity of peers. Plucker and Levy have noted that, "in this culture, there appears to be a great pressure for people to be 'normal' with a considerable stigma associated with giftedness or talent." To counteract this problem, gifted education professionals recommend creating a peer group based on common interests and abilities. The earlier this occurs, the more effective it is likely to be in preventing isolation.

Research suggests that gifted adolescents might have deficiencies in social valuation, mentalization, and social adaptive learning.

Perfectionism

Perfectionism, while considered to have many positive aspects, can be another issue for gifted individuals. It is encouraged by the fact that gifted individuals tend to be easily successful in much of what they do.

Healthy perfectionism refers to having high standards, a desire to achieve, conscientiousness, or high levels of responsibility. It is likely to be a virtue rather than a problem, even if gifted children may have difficulty with healthy perfectionism because they set standards that would be appropriate to their mental age (the level at which they think), but they cannot always meet them because they are bound to a younger body, or the social environment is restrictive. In such cases, outsiders may call some behavior perfectionism, while for the gifted this may be their standard. It has been said that perfectionism "becomes desirable when it stimulates the healthy pursuit of excellence."

Some believe that perfectionism can be unhealthy. Unhealthy perfectionism stems from equating one's worth as a human being to one's achievements, and the simultaneous belief that any work less than perfect is unacceptable and will lead to criticism. Because perfection in the majority of human activities is neither desirable, nor possible, this cognitive distortion creates self-doubt, performance anxiety and ultimately procrastination.

The unhealthy perfectionism can be triggered or further exaggerated by parents, siblings or classmates with good or ill intentions. Parents are usually proud and will extensively praise the gifted child. On the other hand, siblings, comrades and school bullies will generally become jealous of the intellectual ease of the gifted child and tease him or her about any minor imperfection in his or her work, strength, clothes, appearance, or behavior. Either approach—positive reinforcement from parents, or negative reactions from siblings and comrades for minor flaws—will push these kids into considering their worth to their peers as equal to their abilities and consider any imperfection as a serious defect in themselves. This unhealthy perfectionism can be further exaggerated when the child counter-attacks those who have mocked him with their own weapons, i.e. their lower abilities, thus creating disdain in himself for low or even average performance.

There are many theories that try to explain the correlation between perfectionism and giftedness. Perfectionism becomes a problem as it frustrates and inhibits achievements.

D. E. Hamachek identified six specific, overlapping types of behavior associated with perfectionism. They include:

• Depression
• A nagging "I should" feeling
• Shame and guilt feelings
• Face-saving behavior
• Shyness and procrastination
• Self-deprecation.

Underachievement

There is often a stark gap between the abilities of the gifted individual and their actual accomplishments. Many gifted students will perform extremely well on standardized or reasoning tests, only to fail a class exam. This disparity can result from various factors, such as loss of interest in classes that are too easy or negative social consequences of being perceived as smart. Underachievement can also result from emotional or psychological factors, including depression, anxiety, perfectionism, or self-sabotage.

An often-overlooked contributor to underachievement is undiagnosed learning differences. A gifted individual is less likely to be diagnosed with a learning disorder than a non-gifted classmate, as the gifted child can more readily compensate for their paucities. This masking effect is dealt with by understanding that a difference of one standard deviation between scores constitutes a learning disability even if all of the scores are above average.

In addition, many gifted students may underachieve because they have grown to believe that because of their intelligence, things should always come easily to them, and thus may lag behind their non-gifted peers in the work ethic required to learn things that do not come immediately to them.

Some gifted children may not be aware that they are gifted, and not just average. One apparently effective way to attempt to reverse underachievement in gifted children includes educating teachers to provide enrichment projects based on students’ strengths and interests without attracting negative attention from peers.

Depression

It has been thought in the past that there is a correlation between giftedness and depression.^{[citation needed]} This is not an established research finding. As Reis and Renzulli mention,

With the exception of creatively gifted adolescents who are talented in writing or the visual arts, studies do not confirm that gifted individuals manifest significantly higher or lower rates or severity of depression than those for the general population. Gifted children's advanced cognitive abilities, social isolation, sensitivity, and uneven development may cause them to face some challenging social and emotional issues, but their problem-solving abilities, advanced social skills, moral reasoning, out-of-school interests, and satisfaction in achievement may help them to be more resilient.

There is also no research that points to suicide attempt rates being higher in gifted adolescents than other adolescents.

Memory

From Wikipedia, the free encyclopedia

Overview of the forms and functions of memory.

Memory is the faculty of the mind by which information is encoded, stored, and retrieved when needed.

Memory is vital to experiences and related to limbic systems, it is the retention of information over time for the purpose of influencing future action. If we could not remember past events, we could not learn or develop language, relationships, or personal identity (Eysenck, 2012).

Often memory is understood as an informational processing system with explicit and implicit functioning that is made up of a sensory processor, short-term (or working) memory, and long-term memory (Baddely, 2007). This can be related to the neuron. The sensory processor allows information from the outside world to be sensed in the form of chemical and physical stimuli and attended to with various levels of focus and intent. Working memory serves as an encoding and retrieval processor. Information in the form of stimuli is encoded in accordance with explicit or implicit functions by the working memory processor. The working memory also retrieves information from previously stored material. Finally, the function of long-term memory is to store data through various categorical models or systems (Baddely, 2007).

Explicit and implicit functions of memory are also known as declarative and non-declarative systems (Squire, 2009). These systems involve the purposeful intention of memory retrieval and storage, or lack thereof. Declarative, or explicit, memory is the conscious storage and recollection of data (Graf & Schacter, 1985). Under declarative memory resides semantic and episodic memory. Semantic memory refers to memory that is encoded with specific meaning (Eysenck, 2012), while episodic memory refers to information that is encoded along a spatial and temporal plane (Schacter & Addis, 2007; Szpunar, 2010). Declarative memory is usually the primary process thought of when referencing memory (Eysenck, 2012).

Non-declarative, or implicit, memory is the unconscious storage and recollection of information (Foerde & Poldrack, 2009). An example of a non-declarative process would be the unconscious learning or retrieval of information by way of procedural memory, or a priming phenomenon (Eysenck, 2012; Foerde & Poldrack, 2009; Tulving & Schacter, 1990). Priming is the process of subliminally arousing specific responses from memory and shows that not all memory is consciously activated (Tulving & Schacter, 1990), whereas procedural memory is the slow and gradual learning of skills that often occurs without conscious attention to learning (Eysenck, 2012; Foerde & Poldrack, 2009).

Memory is not a perfect processor, and is affected by many factors. The manner information is encoded, stored, and retrieved can all be corrupted. The amount of attention given new stimuli can diminish the amount of information that becomes encoded for storage (Eysenck, 2012). Also, the storage process can become corrupted by physical damage to areas of the brain that are associated with memory storage, such as the hippocampus (Squire, 2009). Finally, the retrieval of information from long-term memory can be disrupted because of decay within long-term memory (Eysenck, 2012). Normal functioning, decay over time, and brain damage all affect the accuracy and capacity of memory.

Memory loss is usually described as forgetfulness or amnesia.

Sensory memory

Sensory memory holds sensory information less than one second after an item is perceived. The ability to look at an item and remember what it looked like with just a split second of observation, or memorization, is the example of sensory memory. It is out of cognitive control and is an automatic response. With very short presentations, participants often report that they seem to "see" more than they can actually report. The first experiments exploring this form of sensory memory were precisely conducted by George Sperling (1963) using the "partial report paradigm". Subjects were presented with a grid of 12 letters, arranged into three rows of four. After a brief presentation, subjects were then played either a high, medium or low tone, cuing them which of the rows to report. Based on these partial report experiments, Sperling was able to show that the capacity of sensory memory was approximately 12 items, but that it degraded very quickly (within a few hundred milliseconds). Because this form of memory degrades so quickly, participants would see the display but be unable to report all of the items (12 in the "whole report" procedure) before they decayed. This type of memory cannot be prolonged via rehearsal.

Three types of sensory memories exist. Iconic memory is a fast decaying store of visual information; a type of sensory memory that briefly stores an image which has been perceived for a small duration. Echoic memory is a fast decaying store of auditory information, another type of sensory memory that briefly stores sounds that have been perceived for short durations. Haptic memory is a type of sensory memory that represents a database for touch stimuli.

Short-term memory

Short-term memory is also known as working memory. Short-term memory allows recall for a period of several seconds to a minute without rehearsal. Its capacity is also very limited: George A. Miller (1956), when working at Bell Laboratories, conducted experiments showing that the store of short-term memory was 7±2 items (the title of his famous paper, "The magical number 7±2"). Modern estimates of the capacity of short-term memory are lower, typically of the order of 4–5 items; however, memory capacity can be increased through a process called chunking. For example, in recalling a ten-digit telephone number, a person could chunk the digits into three groups: first, the area code (such as 123), then a three-digit chunk (456) and lastly a four-digit chunk (7890). This method of remembering telephone numbers is far more effective than attempting to remember a string of 10 digits; this is because we are able to chunk the information into meaningful groups of numbers. This may be reflected in some countries in the tendency to display telephone numbers as several chunks of two to four numbers.

Short-term memory is believed to rely mostly on an acoustic code for storing information, and to a lesser extent a visual code. Conrad (1964) found that test subjects had more difficulty recalling collections of letters that were acoustically similar (e.g. E, P, D). Confusion with recalling acoustically similar letters rather than visually similar letters implies that the letters were encoded acoustically. Conrad's (1964) study, however, deals with the encoding of written text; thus, while memory of written language may rely on acoustic components, generalisations to all forms of memory cannot be made.

Long-term memory

Olin Levi Warner, Memory (1896). Library of Congress Thomas Jefferson Building, Washington, D.C.

The storage in sensory memory and short-term memory generally has a strictly limited capacity and duration, which means that information is not retained indefinitely. By contrast, long-term memory can store much larger quantities of information for potentially unlimited duration (sometimes a whole life span). Its capacity is immeasurable. For example, given a random seven-digit number we may remember it for only a few seconds before forgetting, suggesting it was stored in our short-term memory. On the other hand, we can remember telephone numbers for many years through repetition; this information is said to be stored in long-term memory.

While short-term memory encodes information acoustically, long-term memory encodes it semantically: Baddeley (1966) discovered that, after 20 minutes, test subjects had the most difficulty recalling a collection of words that had similar meanings (e.g. big, large, great, huge) long-term. Another part of long-term memory is episodic memory, "which attempts to capture information such as 'what', 'when' and 'where'". With episodic memory, individuals are able to recall specific events such as birthday parties and weddings.

Short-term memory is supported by transient patterns of neuronal communication, dependent on regions of the frontal lobe (especially dorsolateral prefrontal cortex) and the parietal lobe. Long-term memory, on the other hand, is maintained by more stable and permanent changes in neural connections widely spread throughout the brain. The hippocampus is essential (for learning new information) to the consolidation of information from short-term to long-term memory, although it does not seem to store information itself. It was thought that without the hippocampus new memories were unable to be stored into long-term memory and that there would be a very short attention span, as first gleaned from patient Henry Molaison after what was thought to be the full removal of both his hippocampi. More recent examination of his brain, post-mortem, shows that the hippocampus was more intact than first thought, throwing theories drawn from the initial data into question. The hippocampus may be involved in changing neural connections for a period of three months or more after the initial learning.

Research has suggested that long-term memory storage in humans may be maintained by DNA methylation, and the 'prion' gene.

Multi-store model

The multi-store model (also known as Atkinson–Shiffrin memory model) was first described in 1968 by Atkinson and Shiffrin.

The multi-store model has been criticised for being too simplistic. For instance, long-term memory is believed to be actually made up of multiple subcomponents, such as episodic and procedural memory. It also proposes that rehearsal is the only mechanism by which information eventually reaches long-term storage, but evidence shows us capable of remembering things without rehearsal.
The model also shows all the memory stores as being a single unit whereas research into this shows differently. For example, short-term memory can be broken up into different units such as visual information and acoustic information. In a study by Zlonoga and Gerber (1986), patient 'KF' demonstrated certain deviations from the Atkinson–Shiffrin model. Patient KF was brain damaged, displaying difficulties regarding short-term memory. Recognition of sounds such as spoken numbers, letters, words and easily identifiable noises (such as doorbells and cats meowing) were all impacted. Visual short-term memory was unaffected, suggesting a dichotomy between visual and audial memory.

Working memory

The working memory model

In 1974 Baddeley and Hitch proposed a "working memory model" that replaced the general concept of short-term memory with an active maintenance of information in the short-term storage. In this model, working memory consists of three basic stores: the central executive, the phonological loop and the visuo-spatial sketchpad. In 2000 this model was expanded with the multimodal episodic buffer (Baddeley's model of working memory).

The central executive essentially acts as an attention sensory store. It channels information to the three component processes: the phonological loop, the visuo-spatial sketchpad, and the episodic buffer.

The phonological loop stores auditory information by silently rehearsing sounds or words in a continuous loop: the articulatory process (for example the repetition of a telephone number over and over again). A short list of data is easier to remember.

The visuospatial sketchpad stores visual and spatial information. It is engaged when performing spatial tasks (such as judging distances) or visual ones (such as counting the windows on a house or imagining images).

The episodic buffer is dedicated to linking information across domains to form integrated units of visual, spatial, and verbal information and chronological ordering (e.g., the memory of a story or a movie scene). The episodic buffer is also assumed to have links to long-term memory and semantical meaning.

The working memory model explains many practical observations, such as why it is easier to do two different tasks (one verbal and one visual) than two similar tasks (e.g., two visual), and the aforementioned word-length effect. However, the concept of a central executive as noted here has been criticised as inadequate and vague. Working memory is also the premise for what allows us to do everyday activities involving thought. It is the section of memory where we carry out thought processes and use them to learn and reason about topics.

Types

Researchers distinguish between recognition and recall memory. Recognition memory tasks require individuals to indicate whether they have encountered a stimulus (such as a picture or a word) before. Recall memory tasks require participants to retrieve previously learned information. For example, individuals might be asked to produce a series of actions they have seen before or to say a list of words they have heard before.

By information type

Topographic memory involves the ability to orient oneself in space, to recognize and follow an itinerary, or to recognize familiar places. Getting lost when traveling alone is an example of the failure of topographic memory.

Flashbulb memories are clear episodic memories of unique and highly emotional events. People remembering where they were or what they were doing when they first heard the news of President Kennedy's assassination, the Sydney Siege or of 9/11 are examples of flashbulb memories.

Anderson (1976) divides long-term memory into declarative (explicit) and procedural (implicit) memories.

Declarative

Declarative memory requires conscious recall, in that some conscious process must call back the information. It is sometimes called explicit memory, since it consists of information that is explicitly stored and retrieved.

Declarative memory can be further sub-divided into semantic memory, concerning principles and facts taken independent of context; and episodic memory, concerning information specific to a particular context, such as a time and place. Semantic memory allows the encoding of abstract knowledge about the world, such as "Paris is the capital of France". Episodic memory, on the other hand, is used for more personal memories, such as the sensations, emotions, and personal associations of a particular place or time. Episodic memories often reflect the "firsts" in life such as a first kiss, first day of school or first time winning a championship. These are key events in one's life that can be remembered clearly. Autobiographical memory – memory for particular events within one's own life – is generally viewed as either equivalent to, or a subset of, episodic memory. Visual memory is part of memory preserving some characteristics of our senses pertaining to visual experience. One is able to place in memory information that resembles objects, places, animals or people in sort of a mental image. Visual memory can result in priming and it is assumed some kind of perceptual representational system underlies this phenomenon.

Procedural

In contrast, procedural memory (or implicit memory) is not based on the conscious recall of information, but on implicit learning. It can best be summarized as remembering how to do something. Procedural memory is primarily employed in learning motor skills and should be considered a subset of implicit memory. It is revealed when one does better in a given task due only to repetition – no new explicit memories have been formed, but one is unconsciously accessing aspects of those previous experiences. Procedural memory involved in motor learning depends on the cerebellum and basal ganglia.

A characteristic of procedural memory is that the things remembered are automatically translated into actions, and thus sometimes difficult to describe. Some examples of procedural memory include the ability to ride a bike or tie shoelaces.

By temporal direction

Another major way to distinguish different memory functions is whether the content to be remembered is in the past, retrospective memory, or in the future, prospective memory. Thus, retrospective memory as a category includes semantic, episodic and autobiographical memory. In contrast, prospective memory is memory for future intentions, or remembering to remember (Winograd, 1988). Prospective memory can be further broken down into event- and time-based prospective remembering. Time-based prospective memories are triggered by a time-cue, such as going to the doctor (action) at 4pm (cue). Event-based prospective memories are intentions triggered by cues, such as remembering to post a letter (action) after seeing a mailbox (cue). Cues do not need to be related to the action (as the mailbox/letter example), and lists, sticky-notes, knotted handkerchiefs, or string around the finger all exemplify cues that people use as strategies to enhance prospective memory.

Study techniques

To assess infants

Infants do not have the language ability to report on their memories and so verbal reports cannot be used to assess very young children's memory. Throughout the years, however, researchers have adapted and developed a number of measures for assessing both infants' recognition memory and their recall memory. Habituation and operant conditioning techniques have been used to assess infants' recognition memory and the deferred and elicited imitation techniques have been used to assess infants' recall memory.

Techniques used to assess infants' recognition memory include the following:

• Visual paired comparison procedure (relies on habituation): infants are first presented with pairs of visual stimuli, such as two black-and-white photos of human faces, for a fixed amount of time; then, after being familiarized with the two photos, they are presented with the "familiar" photo and a new photo. The time spent looking at each photo is recorded. Looking longer at the new photo indicates that they remember the "familiar" one. Studies using this procedure have found that 5- to 6-month-olds can retain information for as long as fourteen days.
• Operant conditioning technique: infants are placed in a crib and a ribbon that is connected to a mobile overhead is tied to one of their feet. Infants notice that when they kick their foot the mobile moves – the rate of kicking increases dramatically within minutes. Studies using this technique have revealed that infants' memory substantially improves over the first 18-months. Whereas 2- to 3-month-olds can retain an operant response (such as activating the mobile by kicking their foot) for a week, 6-month-olds can retain it for two weeks, and 18-month-olds can retain a similar operant response for as long as 13 weeks.

Techniques used to assess infants' recall memory include the following:

• Deferred imitation technique: an experimenter shows infants a unique sequence of actions (such as using a stick to push a button on a box) and then, after a delay, asks the infants to imitate the actions. Studies using deferred imitation have shown that 14-month-olds' memories for the sequence of actions can last for as long as four months.
• Elicited imitation technique: is very similar to the deferred imitation technique; the difference is that infants are allowed to imitate the actions before the delay. Studies using the elicited imitation technique have shown that 20-month-olds can recall the action sequences twelve months later.

To assess older children and adults

Researchers use a variety of tasks to assess older children and adults' memory. Some examples are:

• Paired associate learning – when one learns to associate one specific word with another. For example, when given a word such as "safe" one must learn to say another specific word, such as "green". This is stimulus and response.
• Free recall – during this task a subject would be asked to study a list of words and then later they will be asked to recall or write down as many words that they can remember, similar to free response questions. Earlier items are affected by retroactive interference (RI), which means the longer the list, the greater the interference, and the less likelihood that they are recalled. On the other hand, items that have been presented lastly suffer little RI, but suffer a great deal from proactive interference (PI), which means the longer the delay in recall, the more likely that the items will be lost.
• Cued recall – one is given significant hints about the information. This is similar to fill in the blank assessments used in classrooms.
• Recognition – subjects are asked to remember a list of words or pictures, after which point they are asked to identify the previously presented words or pictures from among a list of alternatives that were not presented in the original list. This is similar to multiple choice assessments.
• Detection paradigm – individuals are shown a number of objects and color samples during a certain period of time. They are then tested on their visual ability to remember as much as they can by looking at testers and pointing out whether the testers are similar to the sample, or if any change is present.
• Savings method – compares the speed of originally learning to the speed of relearning it. The amount of time saved measures memory.

Failures

The garden of oblivion, illustration by Ephraim Moses Lilien.

• Transience – memories degrade with the passing of time. This occurs in the storage stage of memory, after the information has been stored and before it is retrieved. This can happen in sensory, short-term, and long-term storage. It follows a general pattern where the information is rapidly forgotten during the first couple of days or years, followed by small losses in later days or years.
• Absentmindedness – Memory failure due to the lack of attention. Attention plays a key role in storing information into long-term memory; without proper attention, the information might not be stored, making it impossible to be retrieved later.

Physiology

Brain areas involved in the neuroanatomy of memory such as the hippocampus, the amygdala, the striatum, or the mammillary bodies are thought to be involved in specific types of memory. For example, the hippocampus is believed to be involved in spatial learning and declarative learning, while the amygdala is thought to be involved in emotional memory.

Damage to certain areas in patients and animal models and subsequent memory deficits is a primary source of information. However, rather than implicating a specific area, it could be that damage to adjacent areas, or to a pathway traveling through the area is actually responsible for the observed deficit. Further, it is not sufficient to describe memory, and its counterpart, learning, as solely dependent on specific brain regions. Learning and memory are usually attributed to changes in neuronal synapses, thought to be mediated by long-term potentiation and long-term depression. However, this has been questioned on computational as well as neurophysiological grounds by the cognitive scientist Charles R. Gallistel and others.

In general, the more emotionally charged an event or experience is, the better it is remembered; this phenomenon is known as the memory enhancement effect. Patients with amygdala damage, however, do not show a memory enhancement effect.

Hebb distinguished between short-term and long-term memory. He postulated that any memory that stayed in short-term storage for a long enough time would be consolidated into a long-term memory. Later research showed this to be false. Research has shown that direct injections of cortisol or epinephrine help the storage of recent experiences. This is also true for stimulation of the amygdala. This proves that excitement enhances memory by the stimulation of hormones that affect the amygdala. Excessive or prolonged stress (with prolonged cortisol) may hurt memory storage. Patients with amygdalar damage are no more likely to remember emotionally charged words than nonemotionally charged ones. The hippocampus is important for explicit memory. The hippocampus is also important for memory consolidation. The hippocampus receives input from different parts of the cortex and sends its output out to different parts of the brain also. The input comes from secondary and tertiary sensory areas that have processed the information a lot already. Hippocampal damage may also cause memory loss and problems with memory storage. This memory loss includes retrograde amnesia which is the loss of memory for events that occurred shortly before the time of brain damage.

Cognitive neuroscience

Cognitive neuroscientists consider memory as the retention, reactivation, and reconstruction of the experience-independent internal representation. The term of internal representation implies that such definition of memory contains two components: the expression of memory at the behavioral or conscious level, and the underpinning physical neural changes (Dudai 2007). The latter component is also called engram or memory traces (Semon 1904). Some neuroscientists and psychologists mistakenly equate the concept of engram and memory, broadly conceiving all persisting after-effects of experiences as memory; others argue against this notion that memory does not exist until it is revealed in behavior or thought (Moscovitch 2007).

One question that is crucial in cognitive neuroscience is how information and mental experiences are coded and represented in the brain. Scientists have gained much knowledge about the neuronal codes from the studies of plasticity, but most of such research has been focused on simple learning in simple neuronal circuits; it is considerably less clear about the neuronal changes involved in more complex examples of memory, particularly declarative memory that requires the storage of facts and events (Byrne 2007). Convergence-divergence zones might be the neural networks where memories are stored and retrieved. Considering that there are several kinds of memory, depending on types of represented knowledge, underlying mechanisms, processes functions and modes of acquisition, it is likely that different brain areas support different memory systems and that they are in mutual relationships in neuronal networks: "components of memory representation are distributed widely across different parts of the brain as mediated by multiple neocortical circuits".

• Encoding. Encoding of working memory involves the spiking of individual neurons induced by sensory input, which persists even after the sensory input disappears (Jensen and Lisman 2005; Fransen et al. 2002). Encoding of episodic memory involves persistent changes in molecular structures that alter synaptic transmission between neurons. Examples of such structural changes include long-term potentiation (LTP) or spike-timing-dependent plasticity (STDP). The persistent spiking in working memory can enhance the synaptic and cellular changes in the encoding of episodic memory (Jensen and Lisman 2005).
• Working memory. Recent functional imaging studies detected working memory signals in both medial temporal lobe (MTL), a brain area strongly associated with long-term memory, and prefrontal cortex (Ranganath et al. 2005), suggesting a strong relationship between working memory and long-term memory. However, the substantially more working memory signals seen in the prefrontal lobe suggest that this area play a more important role in working memory than MTL (Suzuki 2007).
• Consolidation and reconsolidation. Short-term memory (STM) is temporary and subject to disruption, while long-term memory (LTM), once consolidated, is persistent and stable. Consolidation of STM into LTM at the molecular level presumably involves two processes: synaptic consolidation and system consolidation. The former involves a protein synthesis process in the medial temporal lobe (MTL), whereas the latter transforms the MTL-dependent memory into an MTL-independent memory over months to years (Ledoux 2007). In recent years, such traditional consolidation dogma has been re-evaluated as a result of the studies on reconsolidation. These studies showed that prevention after retrieval affects subsequent retrieval of the memory (Sara 2000). New studies have shown that post-retrieval treatment with protein synthesis inhibitors and many other compounds can lead to an amnestic state (Nadel et al. 2000b; Alberini 2005; Dudai 2006). These findings on reconsolidation fit with the behavioral evidence that retrieved memory is not a carbon copy of the initial experiences, and memories are updated during retrieval.

Genetics

Study of the genetics of human memory is in its infancy. A notable initial success was the association of APOE with memory dysfunction in Alzheimer's Disease. The search for genes associated with normally varying memory continues. One of the first candidates for normal variation in memory is the protein KIBRA, which appears to be associated with the rate at which material is forgotten over a delay period. There has been some evidence that memories are stored in the nucleus of neurons.

In infancy

For the inability of adults to retrieve early memories, see Childhood amnesia.

 

Up until the mid-1980s it was assumed that infants could not encode, retain, and retrieve information. A growing body of research now indicates that infants as young as 6-months can recall information after a 24-hour delay. Furthermore, research has revealed that as infants grow older they can store information for longer periods of time; 6-month-olds can recall information after a 24-hour period, 9-month-olds after up to five weeks, and 20-month-olds after as long as twelve months. In addition, studies have shown that with age, infants can store information faster. Whereas 14-month-olds can recall a three-step sequence after being exposed to it once, 6-month-olds need approximately six exposures in order to be able to remember it.

Although 6-month-olds can recall information over the short-term, they have difficulty recalling the temporal order of information. It is only by 9 months of age that infants can recall the actions of a two-step sequence in the correct temporal order – that is, recalling step 1 and then step 2. In other words, when asked to imitate a two-step action sequence (such as putting a toy car in the base and pushing in the plunger to make the toy roll to the other end), 9-month-olds tend to imitate the actions of the sequence in the correct order (step 1 and then step 2). Younger infants (6-month-olds) can only recall one step of a two-step sequence. Researchers have suggested that these age differences are probably due to the fact that the dentate gyrus of the hippocampus and the frontal components of the neural network are not fully developed at the age of 6-months.

In fact, the term 'infantile amnesia' refers to the phenomenon of accelerated forgetting during infancy. Importantly, infantile amnesia is not unique to humans, and preclinical research (using rodent models) provides insight into the precise neurobiology of this phenomenon. A review of the literature from behavioral neuroscientist Dr Jee Hyun Kim suggests that accelerated forgetting during early life is at least partly due to rapid growth of the brain during this period.

Aging

One of the key concerns of older adults is the experience of memory loss, especially as it is one of the hallmark symptoms of Alzheimer's disease. However, memory loss is qualitatively different in normal aging from the kind of memory loss associated with a diagnosis of Alzheimer's (Budson & Price, 2005). Research has revealed that individuals' performance on memory tasks that rely on frontal regions declines with age. Older adults tend to exhibit deficits on tasks that involve knowing the temporal order in which they learned information; source memory tasks that require them to remember the specific circumstances or context in which they learned information; and prospective memory tasks that involve remembering to perform an act at a future time. Older adults can manage their problems with prospective memory by using appointment books, for example.

Disorders

Much of the current knowledge of memory has come from studying memory disorders, particularly amnesia. Loss of memory is known as amnesia. Amnesia can result from extensive damage to: (a) the regions of the medial temporal lobe, such as the hippocampus, dentate gyrus, subiculum, amygdala, the parahippocampal, entorhinal, and perirhinal cortices or the (b) midline diencephalic region, specifically the dorsomedial nucleus of the thalamus and the mammillary bodies of the hypothalamus. There are many sorts of amnesia, and by studying their different forms, it has become possible to observe apparent defects in individual sub-systems of the brain's memory systems, and thus hypothesize their function in the normally working brain. Other neurological disorders such as Alzheimer's disease and Parkinson's disease can also affect memory and cognition. Hyperthymesia, or hyperthymesic syndrome, is a disorder that affects an individual's autobiographical memory, essentially meaning that they cannot forget small details that otherwise would not be stored. Korsakoff's syndrome, also known as Korsakoff's psychosis, amnesic-confabulatory syndrome, is an organic brain disease that adversely affects memory by widespread loss or shrinkage of neurons within the prefrontal cortex.

While not a disorder, a common temporary failure of word retrieval from memory is the tip-of-the-tongue phenomenon. Sufferers of Anomic aphasia (also called Nominal aphasia or Anomia), however, do experience the tip-of-the-tongue phenomenon on an ongoing basis due to damage to the frontal and parietal lobes of the brain.

Influencing factors

Interference can hamper memorization and retrieval. There is retroactive interference, when learning new information makes it harder to recall old information and proactive interference, where prior learning disrupts recall of new information. Although interference can lead to forgetting, it is important to keep in mind that there are situations when old information can facilitate learning of new information. Knowing Latin, for instance, can help an individual learn a related language such as French – this phenomenon is known as positive transfer.

Stress

Stress has a significant effect on memory formation and learning. In response to stressful situations, the brain releases hormones and neurotransmitters (ex. glucocorticoids and catecholamines) which affect memory encoding processes in the hippocampus. Behavioural research on animals shows that chronic stress produces adrenal hormones which impact the hippocampal structure in the brains of rats. An experimental study by German cognitive psychologists L. Schwabe and O. Wolf demonstrates how learning under stress also decreases memory recall in humans. In this study, 48 healthy female and male university students participated in either a stress test or a control group. Those randomly assigned to the stress test group had a hand immersed in ice cold water (the reputable SECPT or 'Socially Evaluated Cold Pressor Test') for up to three minutes, while being monitored and videotaped. Both the stress and control groups were then presented with 32 words to memorize. Twenty-four hours later, both groups were tested to see how many words they could remember (free recall) as well as how many they could recognize from a larger list of words (recognition performance). The results showed a clear impairment of memory performance in the stress test group, who recalled 30% fewer words than the control group. The researchers suggest that stress experienced during learning distracts people by diverting their attention during the memory encoding process.

However, memory performance can be enhanced when material is linked to the learning context, even when learning occurs under stress. A separate study by cognitive psychologists Schwabe and Wolf shows that when retention testing is done in a context similar to or congruent with the original learning task (i.e., in the same room), memory impairment and the detrimental effects of stress on learning can be attenuated. Seventy-two healthy female and male university students, randomly assigned to the SECPT stress test or to a control group, were asked to remember the locations of 15 pairs of picture cards – a computerized version of the card game "Concentration" or "Memory". The room in which the experiment took place was infused with the scent of vanilla, as odour is a strong cue for memory. Retention testing took place the following day, either in the same room with the vanilla scent again present, or in a different room without the fragrance. The memory performance of subjects who experienced stress during the object-location task decreased significantly when they were tested in an unfamiliar room without the vanilla scent (an incongruent context); however, the memory performance of stressed subjects showed no impairment when they were tested in the original room with the vanilla scent (a congruent context). All participants in the experiment, both stressed and unstressed, performed faster when the learning and retrieval contexts were similar.

This research on the effects of stress on memory may have practical implications for education, for eyewitness testimony and for psychotherapy: students may perform better when tested in their regular classroom rather than an exam room, eyewitnesses may recall details better at the scene of an event than in a courtroom, and persons suffering from post-traumatic stress may improve when helped to situate their memories of a traumatic event in an appropriate context.

Stressful life experiences may be a cause of memory loss as a person ages. Glucocorticoids that are released during stress, damage neurons that are located in the hippocampal region of the brain. Therefore, the more stressful situations that someone encounters, the more susceptible they are to memory loss later on. The CA1 neurons found in the hippocampus are destroyed due to glucocorticoids decreasing the release of glucose and the reuptake of glutamate. This high level of extracellular glutamate allows calcium to enter NMDA receptors which in return kills neurons. Stressful life experiences can also cause repression of memories where a person moves an unbearable memory to the unconscious mind. This directly relates to traumatic events in one's past such as kidnappings, being prisoners of war or sexual abuse as a child.

The more long term the exposure to stress is, the more impact it may have. However, short term exposure to stress also causes impairment in memory by interfering with the function of the hippocampus. Research shows that subjects placed in a stressful situation for a short amount of time still have blood glucocorticoid levels that have increased drastically when measured after the exposure is completed. When subjects are asked to complete a learning task after short term exposure they often have difficulties. Prenatal stress also hinders the ability to learn and memorize by disrupting the development of the hippocampus and can lead to unestablished long term potentiation in the offspring of severely stressed parents. Although the stress is applied prenatally, the offspring show increased levels of glucocorticoids when they are subjected to stress later on in life.

Sleep

Making memories occurs through a three-step process, which can be enhanced by sleep. The three steps are as follows:

1. Acquisition which is the process of storage and retrieval of new information in memory
   
2. Consolidation
   
3. Recall

Sleep affects memory consolidation. During sleep, the neural connections in the brain are strengthened. This enhances the brain's abilities to stabilize and retain memories. There have been several studies which show that sleep improves the retention of memory, as memories are enhanced through active consolidation. System consolidation takes place during slow-wave sleep (SWS). This process implicates that memories are reactivated during sleep, but that the process doesn't enhance every memory. It also implicates that qualitative changes are made to the memories when they are transferred to long-term store during sleep. During sleep, the hippocampus replays the events of the day for the neocortex. The neocortex then reviews and processes memories, which moves them into long-term memory. When one does not get enough sleep it makes it more difficult to learn as these neural connections are not as strong, resulting in a lower retention rate of memories. Sleep deprivation makes it harder to focus, resulting in inefficient learning. Furthermore, some studies have shown that sleep deprivation can lead to false memories as the memories are not properly transferred to long-term memory. One of the primary functions of sleep is thought to be the improvement of the consolidation of information, as several studies have demonstrated that memory depends on getting sufficient sleep between training and test. Additionally, data obtained from neuroimaging studies have shown activation patterns in the sleeping brain that mirror those recorded during the learning of tasks from the previous day, suggesting that new memories may be solidified through such rehearsal.

Construction for general manipulation

Although people often think that memory operates like recording equipment, it is not the case. The molecular mechanisms underlying the induction and maintenance of memory are very dynamic and comprise distinct phases covering a time window from seconds to even a lifetime. In fact, research has revealed that our memories are constructed: "current hypotheses suggest that constructive processes allow individuals to simulate and imagine future episodes, happenings, and scenarios. Since the future is not an exact repetition of the past, simulation of future episodes requires a complex system that can draw on the past in a manner that flexibly extracts and recombines elements of previous experiences – a constructive rather than a reproductive system." People can construct their memories when they encode them and/or when they recall them. To illustrate, consider a classic study conducted by Elizabeth Loftus and John Palmer (1974) in which people were instructed to watch a film of a traffic accident and then asked about what they saw. The researchers found that the people who were asked, "How fast were the cars going when they smashed into each other?" gave higher estimates than those who were asked, "How fast were the cars going when they hit each other?" Furthermore, when asked a week later whether they had seen broken glass in the film, those who had been asked the question with smashed were twice more likely to report that they had seen broken glass than those who had been asked the question with hit. There was no broken glass depicted in the film. Thus, the wording of the questions distorted viewers' memories of the event. Importantly, the wording of the question led people to construct different memories of the event – those who were asked the question with smashed recalled a more serious car accident than they had actually seen. The findings of this experiment were replicated around the world, and researchers consistently demonstrated that when people were provided with misleading information they tended to misremember, a phenomenon known as the misinformation effect.

Research has revealed that asking individuals to repeatedly imagine actions that they have never performed or events that they have never experienced could result in false memories. For instance, Goff and Roediger (1998) asked participants to imagine that they performed an act (e.g., break a toothpick) and then later asked them whether they had done such a thing. Findings revealed that those participants who repeatedly imagined performing such an act were more likely to think that they had actually performed that act during the first session of the experiment. Similarly, Garry and her colleagues (1996) asked college students to report how certain they were that they experienced a number of events as children (e.g., broke a window with their hand) and then two weeks later asked them to imagine four of those events. The researchers found that one-fourth of the students asked to imagine the four events reported that they had actually experienced such events as children. That is, when asked to imagine the events they were more confident that they experienced the events.
Research reported in 2013 revealed that it is possible to artificially stimulate prior memories and artificially implant false memories in mice. Using optogenetics, a team of RIKEN-MIT scientists caused the mice to incorrectly associate a benign environment with a prior unpleasant experience from different surroundings. Some scientists believe that the study may have implications in studying false memory formation in humans, and in treating PTSD and schizophrenia.

Improving

A UCLA research study published in the June 2008 issue of the American Journal of Geriatric Psychiatry found that people can improve cognitive function and brain efficiency through simple lifestyle changes such as incorporating memory exercises, healthy eating, physical fitness and stress reduction into their daily lives. This study examined 17 subjects, (average age 53) with normal memory performance. Eight subjects were asked to follow a "brain healthy" diet, relaxation, physical, and mental exercise (brain teasers and verbal memory training techniques). After 14 days, they showed greater word fluency (not memory) compared to their baseline performance. No long-term follow-up was conducted; it is therefore unclear if this intervention has lasting effects on memory.

There are a loosely associated group of mnemonic principles and techniques that can be used to vastly improve memory known as the art of memory.

The International Longevity Center released in 2001 a report which includes in pages 14–16 recommendations for keeping the mind in good functionality until advanced age. Some of the recommendations are to stay intellectually active through learning, training or reading, to keep physically active so to promote blood circulation to the brain, to socialize, to reduce stress, to keep sleep time regular, to avoid depression or emotional instability and to observe good nutrition.

Memorization is a method of learning that allows an individual to recall information verbatim. Rote learning is the method most often used. Methods of memorizing things have been the subject of much discussion over the years with some writers, such as Cosmos Rossellius using visual alphabets. The spacing effect shows that an individual is more likely to remember a list of items when rehearsal is spaced over an extended period of time. In contrast to this is cramming: an intensive memorization in a short period of time. Also relevant is the Zeigarnik effect which states that people remember uncompleted or interrupted tasks better than completed ones. The so-called Method of loci uses spatial memory to memorize non-spatial information.

In plants

Plants lack a specialized organ devoted to memory retention, and so plant memory has been a controversial topic in recent years. New advances in the field have identified the presence of neurotransmitters in plants, adding to the hypothesis that plants are capable of remembering. Action potentials, a physiological response characteristic of neurons, have been shown to have an influence on plants as well, including in wound responses and photosynthesis. In addition to these homologous features of memory systems in both plants and animals, plants have also been observed to encode, store and retrieve basic short-term memories.

One of the most well-studied plants to show rudimentary memory is the Venus flytrap. Native to the subtropical wetlands of the eastern United States, Venus Fly Traps have evolved the ability to obtain meat for sustenance, likely due to the lack of nitrogen in the soil. This is done by two trap-forming leaf tips that snap shut once triggered by a potential prey. On each lobe, three triggers hairs await stimulation. In order to maximize the benefit to cost ratio, the plant enables a rudimentary form of memory in which two trigger hairs must be stimulated within 30 seconds in order to result in trap closure. This system ensures that the trap only closes when potential prey is within grasp.

The time lapse between trigger hair stimulations suggests that the plant can remember an initial stimulus long enough for a second stimulus to initiate trap closure. This memory isn't encoded in a brain, as plants lack this specialized organ. Rather, information is stored in the form of cytoplasmic calcium levels. The first trigger causes a subthreshold cytoplasmic calcium influx. This initial trigger isn't enough to activate trap closure, and so a subsequent stimulus allows for a secondary influx of calcium. The latter calcium rise superimposes on the initial one, creating an action potential that passes threshold, resulting in trap closure. Researchers, to prove that an electrical threshold must be met to stimulate trap closure, excited a single trigger hair with a constant mechanical stimulus using Ag/AgCl electrodes. The trap closed after only a few seconds. This experiment gave evidence to demonstrate that the electrical threshold, not necessarily the number of trigger hair stimulations, was the contributing factor in Venus Fly Trap memory. It has been shown that trap closure can be blocked using uncouplers and inhibitors of voltage-gated channels. After trap closure, these electrical signals stimulate glandular production of jasmonic acid and hydrolases, allowing for digestion of the prey.

The field of plant neurobiology has gained a large amount of interest over the past decade, leading to an influx of research regarding plant memory. Although the Venus flytrap is one of the more highly studied, many other plants exhibit the capacity to remember, including the Mimosa pudica through an experiment conducted by Monica Gagliano and colleagues in 2013. As the field expands, it is likely that we will learn more about the capacity of a plant to remember.