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Friday, July 31, 2026

Intellectual giftedness

From Wikipedia, the free encyclopedia

Intellectual giftedness is an intellectual ability significantly higher than average and can also be called as high intellectual potential.  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. These consequences sometimes include stigmatizing and social exclusion. 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 2.5 percent of the population—that is, IQs above or around the 130 mark. 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

Since Lewis Terman in 1916, psychometricians and psychologists have sometimes equated giftedness with high IQ. Later 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 that supports 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." (The Improving America's Schools Act of 1994, 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).

Another understanding of giftedness is that of asynchronous development. This asynchrony has also been referred to as "dyssynchrony" (Terrassier 1985). It can be within the person; where the child has distinctly different development levels socially, emotionally, physically, or even between different academic areas. It can also be asynchrony between the child and their social and/or academic environment.

The Columbus Group came together in 1991 to talk about their concerns that the current trends in gifted education focused overwhelmingly on achievement and the future impact these students could have on the world, and were missing focusing on and valuing who those children are in the moment, and what their lived experiences were like. They created a definition of giftedness that centers around asynchrony and intensity, which first appeared in print in an article titled "Giftedness: The View from Within" (Morelock, 1992). It states that:

"Giftedness is asynchronous development in which advanced cognitive abilities and heightened intensity combine to create inner experiences and awareness that are qualitatively different from the norm. This asynchrony increases with higher intellectual capacity. The uniqueness of the gifted renders them particularly vulnerable and requires modifications in parenting, teaching and counseling in order for them to develop optimally."

This definition shares many commonalities with the definitions above, but also emphasizes the parenting and counseling differences gifted students may need to be fully supported.

Neuroscience of giftedness

Since the late 90s, the development of the brain of people with high IQ scores has been shown to be different to that of people with 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 become teenagers.

Identification methods

IQ scores can vary for the same person, so a person does not always belong to the same IQ score range each time the person is tested. (IQ score table data and pupil pseudonyms adapted from description of KABC-II norming study cited in Kaufman 2009.)
PupilKABC-IIWISC-IIIWJ-III
Asher9095111
Brianna125110105
Colin10093101
Danica116127118
Elpha9310593
Fritz106105105
Georgi9510090
Hector112113103
Imelda1049697
Jose1019986
Jorawar817875
Leo116124102

In psychology, identification of giftedness is usually based on IQ scores. The threshold of IQ = 130 is defined by statistical rarity. By convention, the 5% of scores who fall more than two standard deviations from the mean (or more accurately 1.96) are considered atypical. In the case of intelligence, these 5% are partitioned to both sides of the range of scores, and include the 2.5% who score more than two standard deviations below the mean and the 2.5% who score more than two standard deviations above the mean. Because the average of IQ is 100 and its standard deviation is 15, this rule places the threshold for intellectual disability at IQ = 70, and the symmetrical threshold for giftedness at IQ = 130 (rounded). This arbitrary threshold is used by most psychologists in most countries.

While IQ testing has the advantage of providing a standardised basis for the diagnosis of giftedness, psychologists are expected to interpret IQ scores in the context of all available information: standardized intelligence tests ignore actual achievement and can fail to detect giftedness. For example, a specific learning disorder such as dyslexia or dyspraxia can easily decrease scores on intelligence tests and hide true intellectual ability.

In educational settings, many schools in the US 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 solely based on 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". This method is still used by many school districts because it is simple and objective. 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 under-challenging.

IQ classification varies from one publisher to another. IQ tests have poor reliability 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 test manuals have standard score ceilings of 160. However, higher ceilings, including scores into the exceptionally and profoundly gifted range, exist for the WISC-IV and WISC-V, which were specifically normed on large samples of gifted children. 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 noticeable characteristic.

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 are used to using 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 was delayed in speech, 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 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 determine the 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 talk early, 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. Teachers may notice that gifted students tend to hover around them more than the other students. This is because gifted students sometimes think that they cannot relate to the students their own age, so they try to communicate with the teacher.

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 factor of giftedness.

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.

Some children identified as academically gifted may in fact struggle when presented with open-ended tasks that call for creative thinking, particularly with questions that do not have a single, correct answer. In 1981, educator Selma Wassermann interviewed a group of gifted children aged ten to twelve to see them demonstrate higher-order cognitive skills; she posed to them various open-ended questions that demanded creative thinking to solve, such as how they supposed birds learn to fly. The children, not knowing the "correct" answer, did not answer any of her questions. Wassermann wrote of her experience:

Again and again I encounter responses in which the pupils try to manipulate me into helping them "get the right answer." The more I avoid doing this, the more tense they seem. Their dependency, their rigidity, their intolerance for ambiguity, their inability to take cognitive risks and their anxiety are astonishing.

In contrast, when she asked a group of "low achievers" how one would weigh a giraffe, they rose up to the challenge and suggested answers. Wasserman found out that the difference in the responses of the two groups was caused by the gifted students' anxiety and fear of making mistakes brought on by high expectations and pressures coming from parents and teachers. Though the students were highly gifted lesson-learners, the lower-level cognitive task of learning does not automatically carry over into the higher-level tasks of problem-solving or imagination and creativity, and were thus inexperienced in dealing with problems that demand higher-level cognition. The "low achiever" group on the other hand routinely confronted on the street situations that required problem-solving skills, thus enabling them to become "street-wise".

Savantism

Savants are individuals who perform exceptionally in a single field of learning. More often, the terms savant and savantism describe people with a competence level in a single field of learning well beyond what is considered normal, even among the gifted community. Such individuals are alternatively termed idiot savants ─ a term that has been mentioned as early as the eighteenth century. Autistic savantism refers to the exceptional abilities occasionally exhibited by people with autism or other pervasive developmental disorders. These abilities often come with below-age-level functioning in most, if not all areas of skilled performance. The term was introduced in a 1978 article in Psychology Today describing this condition. It is also proposed that there are savants with normal or superior IQ such as those with Autism Spectrum Disorder, who demonstrate special abilities involving numbers, mathematics, mechanical, and spatial skills.

Gifted minority students in the United States

The majority of students enrolled in gifted programs are White; Black and Hispanic students constitute a smaller proportion 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. Poor students are also underrepresented in gifted programs, even more than Black and Hispanic students are.

Lack of equity and access in programs for the gifted has been acknowledged since the early twentieth century. In the 1920s, research by Lillian Steele Proctor pointed to systemic racism as a contributor to the relative invisibility of gifted African American youth. 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, selective referrals and educator bias, and 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 be a part of a school that offers GATE programs. Within GATE programs, 29% of the students are Latino and Black, and 57% are White (U.S. Department of Education, 2016).

Weinstein (2002) suggests that some teachers recommend racial minority students— with the exception of 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 influence 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 the 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 is time for gifted and talented education program nominations. Research suggests that teacher expectancy bias can also be diminished 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 of black male students in regards to math. This finding suggests that racial diversity among educators is a 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 were 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. 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 decades; 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 who 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 development

Research over the years has shown mixed results when looking at the psychological well-being of gifted children, according to a 1999 review of research by Neihart. The timeline of research into the impact of giftedness on mental health shows swings from the view point that it increases risk in the late 19th century to Terman's research that the gifted experienced fewer adjustment issues than others. In 1981, a gifted high school student died of suicide and "the phrase, 'social and emotional needs of the gifted' was coined." (Neihart, 1999, p. 10). This event also sparked the birth of the organization SENG, founded by Dr. James T. Webb, as a way to support and educate the gifted community about these needs.

A 2016 review of research facilitated by the National Association for Gifted Children (NAGC) in the United States continues to show that, as a whole, gifted children and young adults are not more susceptible to social and emotional challenges than their typically developing peers. That does not mean, however, that there is nothing special to consider when we are looking to support gifted individuals on their developmental journey.

Asynchrony, as is included in the Columbus Group definition of giftedness above (Morelock, 1992), can manifest as differences in the social and emotional development of gifted students as compared to typically developing peers, and cause them to be "out of step" with others even in a gifted setting. This can lead to challenges for the child that need to be addressed for them to fully develop socially and emotionally.

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. Since the mid-1940s, several high-IQ societies of varying levels of selectivity have been established to help gifted individuals find intellectual peers, the oldest ones being Mensa and Intertel, established in 1946 and 1966 respectively.

Some research suggests that mathematically gifted adolescents might have deficiencies in social valuation and mentalization, while gifted adolescents in general may struggle with social adaptive learning, but these conclusions are not supported by a large literature.

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 simply 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.

Unhealthy perfectionism can be triggered or further exacerbated by parents, siblings, or classmates. Parents are usually proud and will extensively praise the gifted child. On the other hand, siblings, peers, and school bullies may generally become envious of the intellectual ease of the gifted child and tease them about any minor imperfection in their work, strength, clothes, appearance, or behavior. Either approach—positive reinforcement from parents or negative reactions from siblings and peers for minor flaws—may push gifted children into equating their worth amongst their peers to their own abilities; thus, any imperfection could be viewed as a serious defect in themselves. This unhealthy perfectionism can be further exaggerated when the child counters bullying with the same tactics (i.e., insulting the less exceptional abilities of others), thus creating further disdain in themselves for low or even average performance.

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

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

Underachievement

Underachievement is a significant issue for gifted learners. 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. It is estimated that half of gifted children do not perform in school at a level that is up to their abilities. Studies of high school dropouts in the United States estimate that between 18% and 25% of gifted students fail to graduate. 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, low self esteem, or self-sabotage.

An often-overlooked contributor to underachievement is undiagnosed learning disorders. 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. Assessments may also fail to identify some gifted students entirely because their underachieving behaviours keep them from being recognized as exceptional.

Some gifted children may not be aware that they are gifted. 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. Other methods include matching the underachiever with an achieving role model, correcting skill deficiencies and ensuring that proper assessments are in place to identify all learning issues with underachieving students.

Depression

It has been thought in the past that there is a correlation between giftedness and depression. 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.

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Critical period

From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Critical_period

In imprinting and developmental biology, a critical period is a maturational stage in the lifespan of an organism during which the nervous system is especially sensitive to certain environmental stimuli. If, for some reason, the organism does not receive the appropriate stimulus during this "critical period" to learn a given skill or trait, it may be difficult, ultimately less successful, or even impossible, to develop certain associated functions later in life.[citation needed] Functions that are indispensable to an organism's survival, such as vision, are particularly likely to develop during critical periods. "Critical period" also relates to the ability to acquire one's first language. Researchers found that people who passed the "critical period" without having developed communication skills would not acquire their first language fluently.

Some researchers differentiate between 'strong critical periods' and 'weak critical periods' (also known as 'sensitive' periods)—defining 'weak critical periods' / 'sensitive periods' as more extended periods, after which learning is still possible. Other researchers consider these the same phenomenon.

For example, the critical period for the development of a human child's binocular vision is thought to be between three and eight months, with sensitivity to damage extending up to at least three years of age. Further critical periods have been identified for the development of hearing and the vestibular system.

Strong versus weak critical periods

Examples of strong critical periods include monocular deprivation, filial imprinting, monaural occlusion, and Prefrontal Synthesis acquisition. These traits cannot be acquired after the end of the critical period.

Examples of weak critical periods include phoneme tuning, grammar processing, articulation control, vocabulary acquisition, music training, auditory processing, sport training, and many other traits that can be significantly improved by training at any age.

Critical period mechanisms

Critical period opening

Critical periods of plasticity occur in the prenatal brain and continue throughout childhood until adolescence and are very limited during adulthood. Two major factors influence the opening of critical periods: cellular events (i.e. changes in molecular landscape) and sensory experience (i.e. hearing sound, visual input, etc.). Both need to coincide for the critical period to open properly. At the cellular level, critical periods are characterized by maturation of the inhibitory circuits. More precisely, factors such as brain-derived neurotrophic factor (BDNF) and orthodenticle homeobox 2 (Otx2) contribute to the maturation of a major class of inhibitory neurons: parvalbumin-positive interneurons (PV cells). Prior to the onset of the critical period, modulation of this circuit is hampered by early factors such as polysialic acid (PSA). PSA acts, in part, by preventing Otx2 interaction with PV cells. Soon after the opening of the critical period, PSA levels decrease, allowing PV cell maturation by activating inhibitory GABAa receptors that facilitate inhibitory circuit remodeling. Artificially removing PSA, or experimentally manipulating inhibitory transmission can result in early opening of the critical period. While the timing of these molecular events seems to be partially explained by clock genes, experience is crucial as sensory deprivation experiments have been shown to interfere with the proper timing of critical periods.

Activity-dependent competition

Hebbian theory guides the idea of activity-dependent competition: if two neurons both have the potential to make a connection with a cell, the neuron that fires more will make the connection.

Ocular dominance

This phenomenon of activity-dependent competition is especially seen in the formation of ocular dominance columns within the visual system. Early in development, most of the visual cortex is binocular, meaning it receives roughly equal input from both eyes. Normally, as development progresses, the visual cortex will segregate into monocular columns that receive input from only one eye. However, if one eye is patched, or otherwise prevented from receiving sensory input, the visual cortex will shift to favor representation of the uncovered eye. This demonstrates activity-dependent competition and Hebbian theory because inputs from the uncovered eye make and retain more connections than the patched eye.

Axon growth

Axon formation and growth is another key part of plasticity and activity-dependent competition. Axon growth and branching has been shown to be inhibited when the neuron's electrical activity is suppressed below the level of an active neighbor. This shows that axonal growth dynamics are not independent but rather depend on the local circuits within which they are active (i.e. the activity of the other neurons competing for connections).

Microglia

Microglia inherently play a role in synaptic pruning during adolescence. As resident immune cells of the central nervous system, microglia's main role is phagocytosis and engulfment. Studies have found that during critical periods in the visual cortex, neural synapses become the target of microglial phagocytosis. Neurons who received less frequent input from retinal ganglion cells during early postnatal periods were more prone to be engulfed and pruned by microglia, as per monocular deprivation experiments. Similar results were found when manipulating G-coupled purinergic receptors on microglial processes. Blocking these receptors or performing a knockout experiment significantly lowered microglial interactions and synaptic pruning during the early visual cortex critical period. More recently, the expression of the complement component 4 gene has been found to significantly contribute to abnormally high levels of microglial synaptic pruning during early stages of development in the neurons and microglia of schizophrenics, suggesting a genomic connection between the immune system and critical periods.

Spine motility

Dendritic spine motility is the altering of the dendritic morphology of a neuron, specifically the appearing and disappearing of the small protrusions known as spines. In early postnatal development, spine motility has been found to be at very high levels. Due to its most pronounced occurrence during postnatal days 11 through 15, spine motility is thought to have a role in neurogenesis. Motility levels significantly decrease before the start of the visual cortex critical period and monocular deprivation experiments show that motility levels steadily decrease until the critical period is over, hinting that motility might not be explicitly involved in this process. However, binocular deprivation before eye-opening resulted in a significant up-regulation of spine motility until the peak of the critical period, resulting in controversial findings regarding the role of dendritic spine motility.

Excitatory-inhibitory balance

Another critical component of neuronal plasticity is the balance of excitatory and inhibitory inputs. Early in development, GABA, the major inhibitory neurotransmitter in the adult brain, exhibits an excitatory effect on its target neurons. However, due to changes in internal chloride levels due to the up-regulation of potassium chloride pumps, GABA then switches to inhibitory synaptic transmission. The maturation of the GABAergic inhibitory system helps to trigger the onset of critical periods. Strengthened GABAergic systems can induce an early critical period, while weaker GABAergic inputs can delay or even prevent plasticity. Inhibition also guides plasticity once the critical period has begun. For example, lateral inhibition is especially important in guiding columnar formation in the visual cortex. Hebbian theory provides insight on the importance of inhibition within neural networks: without inhibition, there would be more synchronous firing and therefore more connections, but with inhibition, fewer excitatory signals get through, allowing only the more salient connections to mature.

Critical period closure

Perineuronal nets

Critical period closure has been shown to be modulated by the maturation of inhibitory circuits, mediated by the formation of perineuronal nets around inhibitory neurons. Perineuronal nets (PNNs) are structures in the extracellular matrix formed by chondroitin sulfate proteoglycans, hyaluronan, and link proteins. These structures envelop the soma of inhibitory neurons in the central nervous system, appearing with age to stabilize mature circuits. PNN development coincides with the closure of critical periods, and both PNN formation and critical period timing is delayed in dark-rearing. For example, PNN digestion by ABC chondroitinase in rats leads to a shift in ocular dominance upon monocular deprivation, which is normally restricted to its critical period much earlier in development.

Additionally, PNNs are negatively charged, which is theorized to create a cation-rich environment around cells, potentially leading to an increased firing rate of inhibitory neurons, thereby allowing for increased inhibition after the formation of PNNs and helping to close the critical period. The role of PNNs in critical period closure is further supported by the finding that fast-spiking parvalbulmin-positive interneurons are often surrounded by PNNs.

Perineuronal nets have also been found to contain chemorepulsive factors, such as semaphorin3A, which restrict axon growth necessary for plasticity during critical periods. In all, these data suggest a role for PNNs in the maturation of CNS inhibition, the prevention of plastic axonal growth, and subsequently, critical period closure.

Myelin

Another mechanism that closes the critical period is myelination. Myelin sheaths are formed by oligodendrocytes in the CNS that wrap around segments of axons to increase their firing speed. Myelin is formed in the early stages of development and progresses in waves, with brain areas of later phylogenetic development (i.e. those associated with "higher" brain functions like the frontal lobes) having later myelination. The maturation of myelination in intracortical layers coincides with critical period closure in mice, which has led to further research on the role of myelination on critical period duration.

Myelin is known to bind many different axonal growth inhibitors that prevent plasticity seen in critical periods. The Nogo receptor is expressed in myelin and binds to the axonal growth inhibitors Nogo and Myelin-associated glycoprotein (MAG) (among others), preventing axon growth in mature, myelinated neurons. Instead of affecting the timing of the critical period, mutations of the Nogo receptor prolong the critical period temporarily. A mutation of the Nogo receptor in mice was found to extend the critical period for monocular dominance from around 20–32 days to 45 or 120 days, suggesting a likely role of the myelin Nogo receptor in critical period closure.

Additionally, the effects of myelination are temporally limited, since myelination itself may have its own critical period and timing. Research has shown that social isolation of mice leads to reduced myelin thickness and poor working memory, but only during a juvenile critical period. In primates, isolation is correlated with abnormal changes in white matter potentially due to decreased myelination.

In all, myelin and its associated receptors bind several important axonal growth inhibitors which help close the critical period. The timing of this myelination, however, is dependent on the brain region and external factors such as the social environment.

Neuromodulation

While the presence or absence of sensory experiences most robustly shapes brain development during the critical period, the behavioral context (i.e. the amount of attention, arousal, fear and reward experienced) concurrent with the sensory inputs have been suggested to be important in regulating the brain remodeling mechanisms. In terms of brain connectivity, these behavioral and contextual inputs activate the neuromodulatory system, which have substantial connectivity to the cortex. The molecular effectors released by the neuromodulatory system are called neuromodulators, which include acetylcholine, dopamine, and noradrenaline among others. Investigating the effect of these molecules, as well as the neurons that release and bind them, has been one approach to elucidate the biology of neuromodulation. Research using this approach has highlighted the role of neuromodulation in sensory processing during the critical period. For example, in kittens, a shift in ocular dominance resulting from monocular deprivation during the critical period is reduced by combined destruction of noradrenergic and cholinergic neurons. In addition, prenatal exposure to selective serotonin reuptake inhibitors (SSRI) causes a shift in perceptual narrowing on language to earlier in development. On the other hand, neuromodulatory stimulation has been shown to induce brain plasticity in adult mice. While being subjected to cholinergic or dopaminergic stimulation, adult mice listening to a tone of specific frequency exhibited expansion of the tonotopic area in the auditory cortex that responds specifically to sounds of that frequency.

Mechanistically, neuromodulation is increasingly being recognized for its fine-tuning of the PV cell-mediated inhibition of excitatory pyramidal neurons' soma. Central to the neuromodulatory regulation of PV cell activity is the existence of distinct subsets of inhibitory neurons, which are responsive to activation by neuromodulators and which inhibit PV cells. Within these cells, some also inhibit specific pyramidal cell dendrites. By inhibiting PV cells activity, the neuromodulator-sensitive inhibitory cells such as those expressing vasoactive intestinal peptide (VIP) or somatostatin (SST) lift the inhibition of the pyramidal neurons; in other words, the activity of VIP and SST-expressing cells result in the disinhibition of pyramidal neurons. Then, by inhibiting only certain dendritic branches of these now dis-inhibited pyramidal neurons, the neuromodulation-activated cells allow select sensory inputs to excite the pyramidal neurons and be represented in the brain circuitry. Thus, in a landscape of global inhibition by maturing inhibitory signaling, neuromodulation allows windows of dis-inhibition, temporally and spatially, that allow behaviorally important sensory inputs the opportunity to influence the brain.

Linguistics

First language acquisition

The critical period hypothesis (CPH) states that the first few years of life constitute the time during which language develops readily and after which (sometime between age 5 and puberty) language acquisition is much more difficult and ultimately less successful. The hypothesis that language is acquired during a critical period was first proposed by neurologists Wilder Penfield and Lamar Roberts in 1959 and popularized by linguist Eric Lenneberg in 1967. Lenneberg argued for the hypothesis based on evidence that children who experience brain injury early in life develop far better language skills than adults with similar injuries.

Maria Montessori was one of the earlier educators who brought attention to this phenomenon and called it "sensitive periods", which is one of the pillars of her philosophy of education.

The two most famous cases of children who failed to acquire language after the critical period are the feral children Victor of Aveyron and Genie. However, the tragic circumstances of these cases and the moral and ethical impermissibility of replicating them make it difficult to draw conclusions about them. The children may have been cognitively disabled from infancy, or their inability to develop language may have resulted from the profound neglect and abuse they suffered.

Many subsequent researchers have further developed the CPH, most notably Elissa Newport and Rachel Mayberry. Studies conducted by these researchers demonstrated that profoundly deaf individuals who are not exposed to a sign language as children never achieve full proficiency, even after 30 years of daily use. While the effect is most profound for individuals who receive no sign language input until after the age of 12, even those deaf people who began learning a sign language at age 5 were significantly less fluent than native deaf signers (whose exposure to a sign language began at birth). Early language exposure also affects the ability to learn a second language later in life: profoundly deaf individuals with early language exposure achieve comparable levels of proficiency in a second language to hearing individuals with early language exposure. In contrast, deaf individuals without early language exposure perform far worse.

Other evidence comes from neuropsychology where it is known that adults well beyond the critical period are more likely to suffer permanent language impairment from brain damage than are children, believed to be due to youthful resiliency of neural reorganization.

Steven Pinker discusses the CPH in his book, The Language Instinct. According to Pinker, language must be viewed as a concept rather than a specific language because the sounds, grammar, meaning, vocabulary, and social norms play an important role in the acquisition of language. Physiological changes in the brain are also conceivable causes for the terminus of the critical period for language acquisition. As language acquisition is crucial during this phase, similarly infant–parent attachment is crucial for social development of the infant. An infant learns to trust and feel safe with the parent, but there are cases in which the infant might be staying at an orphanage where it does not receive the same attachment with their caregiver. Research shows that infants who were unable to develop this attachment had major difficulty in keeping close relationships, and had maladaptive behaviors with adopted parents.

The discussion of language critical period suffers from the lack of a commonly accepted definition of language. Some aspects of language, such as phoneme tuning, grammar processing, articulation control, and vocabulary acquisition can be significantly improved by training at any age and therefore have weak critical periods. Other aspects of language, such as prefrontal synthesis, have strong critical periods and cannot be acquired after the end of the critical period. Consequently, when language is discussed in general, without dissection into components, arguments can be constructed both in favor and against the strong critical period of L1 acquisition.

Second language acquisition

The theory has often been extended to a critical period for second language acquisition (SLA), which has influenced researchers in the field on both sides of the spectrum, supportive and unsupportive of CPH, to explore. However, the nature of this phenomenon has been one of the most fiercely debated issues in psycholinguistics and cognitive science in general for decades.

Certainly, older learners of a second language rarely achieve the native-like fluency that younger learners display, despite often progressing faster than children in the initial stages. This is generally accepted as evidence supporting the CPH. Incorporating the idea, "younger equals better" by Penfield, David Singleton (1995) states that in learning a second language there are many exceptions, noting that five percent of adult bilinguals master a second language even though they begin learning it when they are well into adulthood—long after any critical period has presumably come to a close. The critical period hypothesis holds that first language acquisition must occur before cerebral lateralization completes, at about the age of puberty. One prediction of this hypothesis is that second language acquisition is relatively fast, successful, and qualitatively similar to first language only if it occurs before the age of puberty. To grasp a better understanding of SLA, it is essential to consider linguistic, cognitive, and social factors rather than age alone, as they are all essential to the learner's language acquisition.

Over the years, researchers have tried to find evidence in support of or against the critical periods for second language acquisition. Many have found evidence that young children acquire language more easily than adults, but there are also special cases of adults acquiring a second language with native-like proficiency. Thus it has been difficult for researchers to separate correlation from causation.

In 1989, Jacqueline S. Johnson and Elissa L. Newport found support for the claim that second languages are more easily acquired before puberty, or more specifically before the age of seven. They tested second language learners of English who arrived in the United States at various ages ranging from three to thirty-nine, and found that there was a decline in grammatical correctness after the age of seven. Johnson and Newport attributed this claim to a decline in language learning ability with age. Opponents of the critical period argue that the difference in language ability found by Johnson and Newport could be due to the different types of input that children and adults receive; children received reduced input while adults receive more complicated structures.

Additional evidence against a strict critical period is also found in the work of Pallier et al. (2003) who found that children adopted to France from Korea were able to become native-like in their performance of French even after the critical period for phonology. Their experiment may represent a special case where subjects must lose their first language in order to more perfectly acquire their second.

There is also some debate as to how one can judge the native-like quality of the speech participants produce and what exactly it means to be a near-native speaker of a second language. White et al. found that it is possible for non-native speakers of a language to become native-like in some aspects, but those aspects are influenced by their first language.

Recently, a connectionist model has been developed to explain the changes that take place in second language learning assuming that sensitive period affects lexical learning and syntactic learning parts of the system differently, which sheds further light on how first and second language acquisition changes over the course of learners development.

Vision

In mammals, neurons in the brain that process vision actually develop after birth based on signals from the eyes. A landmark experiment by David H. Hubel and Torsten Wiesel (1963) showed that cats that had one eye sewn shut from birth to three months of age (monocular deprivation) only fully developed vision in the open eye. They showed that columns in the primary visual cortex receiving inputs from the other eye took over the areas that would normally receive input from the deprived eye. In general electrophysiological analyses of axons and neurons in the lateral geniculate nucleus showed that the visual receptive field properties was comparable to adult cats. However, the layers of cortex that were deprived had less activity and fewer responses were isolated. The kittens had abnormally small ocular dominance columns (part of the brain that processes sight) connected to the closed eye, and abnormally large, wide columns connected to the open eye. Because the critical period time had elapsed, it would be impossible for the kittens to alter and develop vision in the closed eye. This did not happen to adult cats even when one eye was sewn shut for a year because they had fully developed their vision during their critical period. Later experiments in monkeys found similar results consistent with the strong critical period.

In a follow-up experiment, Hubel and Wiesel (1963) explored the cortical responses present in kittens after binocular deprivation; they found it difficult to find any active cells in the cortex, and the responses they did get were either slow-moving or fast-fatiguing. Furthermore, the cells that did respond selected for edges and bars with distinct orientation preferences. Nevertheless, these kittens developed normal binocularity. Hubel and Wiesel first explained the mechanism, known as orientation selectivity, in the mammalian visual cortex. Orientation tuning, a model that originated with their model, is a concept in which receptive fields of neurons in the LGN excite a cortical simple cell and are arranged in rows. This model was important because it was able to describe a strong critical period for the proper development of normal ocular dominance columns in the lateral geniculate nucleus, and thus able to explain the effects of monocular deprivation during this critical period. The critical period for cats is about three months and for monkeys, about six months.

In a similar experiment, Antonini and Stryker (1993) examined the anatomical changes that can be observed after monocular deprivation. They compared geniculocortical axonal arbors in monocularly deprived animals in the long term (4 weeks) to short term (6–7 days) during the critical period established by Hubel and Wiesel (1993). They found that in the long term, monocular deprivation causes reduced branching at the end of neurons, while the amount of afferents allocated to the nondeprived eye increased. Even in the short term, Antonini and Stryker (1993) found that geniculocortical neurons were similarly affected. This supports the aforementioned concept of a critical period for proper neural development for vision in the cortex.

Studies of people whose sight has been restored after a long blindness (whether from birth or a later point in life) reveal that they cannot necessarily recognize objects and faces (as opposed to color, motion, and simple geometric shapes). Some hypothesize that being blind during childhood prevents some part of the visual system necessary for these higher-level tasks from developing properly. The general belief that a critical period lasts until age 5 or 6 was challenged by a 2007 study that found that older patients could improve these abilities with years of exposure.

Expression of the protein Lynx1 has been associated with the normal end of the critical period for synaptic plasticity in the visual system.

Imprinting

Konrad Lorenz

In psychology, imprinting is any type of rapid learning that occurs in a particular life stage. While this rapid learning is independent of the behavioral outcome, it also establishes it and can affect behavioral responses to different stimuli. Konrad Lorenz is well known for his classic studies of filial imprinting in graylag geese. From 1935 to 1938, he presented himself to a group of newly hatched gosling and took note of how he was instantly accepted, followed, and called to as if he were the one who laid them himself. As the first moving object they encountered, Lorenz studied the phenomenon in how quickly the geese were able to form such an irreversible bond. Through his work he demonstrated that this only developed during a brief "critical period", which was about a few hours after hatching, suggesting a strong critical period.

Lorenz also discovered a long-lasting effect of his studies, and that was a shift in the species' sexual imprinting as a result from imprinting upon a foster mother of a second species. For certain species, when raised by a second one, they develop and retain imprinted preferences and approach the second species they were raised by rather than choose their own, if given a choice.

Imprinting serves as the distinguishing factor between one's own mother and other mother figures. The mother and the infant both identify with each other, this is a strong bonding moment for humans. It provides a sort of model or guide to adult behaviors in addition to other factors such as nurture, protection in infancy, guidance, and nourishment. The imprinting process, Lorenz also found, brought about a sense of familiarity for the young animals. When such a strong bond is formed at such an early stage, it creates a sense of security and comfort for the subject and actually encourages the imprinting behavior.

Pheromones play a key role in the imprinting process, they trigger a biochemical response in the recipient, leading to a confirmed identification in the other individual. If direct contact between mother and infant is not maintained during the critical imprinting period, then the mother goose may reject the infant because she is unfamiliar with her newborn's scent. If that does happen, then the infant's life would be in jeopardy unless it were claimed by a substitute mother, possibly leading to awkward social behavior in later life. In relation to humans, a newborn during the critical period identifies with its mother's and other peoples' scents since its scent is one of the most developed senses at that stage in life. The newborn uses this pheromone identification to seek the people it identifies with, when in times of distress, hunger, and discomfort as a survival skill. Inferences could be made for newborns based upon Lorenz's studies. When imprinting on their mothers, newborns look to them for nourishment, a sense of security, and comfort. Human newborns are among the most helpless known with orangutan newborns ranking second. Newborns of these species have a very limited array of innate survival abilities. Their most important and functional ability is to form bonds with close individuals who are able to keep them alive. Imprinting is a crucial factor of the critical period because it facilitates the newborn's abilities to form bonds with other individuals, from infancy to adulthood.

Auditory processing

Many studies have supported a correlation between the type of auditory stimuli present in the early postnatal environment and the development on the topographical and structural development of the auditory system.

First reports on critical periods came from deaf children and animals that received a cochlear implant to restore hearing. Approximately at the same time, both an electroencephalographic study by Sharma, Dorman and Spahr and an in-vivo investigation of the cortical plasticity in deaf cats by Kral and colleagues demonstrated that the adaptation to the cochlear implant is subject to an early, developmental sensitive period. The closure of sensitive periods likely involves a multitude of processes that in their combination make it difficult to reopen these behaviorally. The understanding of the mechanisms behind critical periods has consequences for medical therapy of hearing loss. M. Merzenich and colleagues showed that during an early critical period, noise exposure can affect the frequency organization of the auditory cortex.

Recent studies have examined the possibility of a critical period for thalamocortical connectivity in the auditory system. For example, Zhou and Merzenich (2008) studied the effects of noise on development in the primary auditory cortex in rats. In their study, rats were exposed to pulsed noise during the critical period and the effect on cortical processing was measured. Rats that were exposed to pulsed noise during the critical period had cortical neurons that were less able to respond to repeated stimuli; the early auditory environment interrupted normal structural organization during development.

In a related study, Barkat, Polley and Hensch (2011) looked at how exposure to different sound frequencies influences the development of the tonotopic map in the primary auditory cortex and the ventral medical geniculate body. In this experiment, mice were reared either in normal environments or in the presence of 7 kHz tones during early postnatal days. They found that mice that were exposed to an abnormal auditory environment during a critical period P11-P15 had an atypical tonotopic map in the primary auditory cortex. These studies support the notion that exposure to certain sounds within the critical period can influence the development of tonotopic maps and the response properties of neurons. Critical periods are important for the development of the brain for the function from a pattern of connectivity. In general, the early auditory environment influences the structural development and response specificity of the primary auditory cortex.

Absolute pitch

Absolute pitch manifests itself almost always before adolescence and rarely if ever among individuals who are first exposed to music after mid-childhood, suggesting that exposure to music or similar phenomena (e.g., tonal languages) in early to mid-childhood is a necessary condition for its development or refinement. Studies that ask musicians and non-musicians to sing or hum well-known popular songs that have definitive recordings (and hence are sung in standardized keys) show that—on average—participants sing within a semitone of the standardized key but that outside the small subset of participants with absolute pitch there is broad variation (the "bell curve" that reflects the degree of approximation to the standard key is broad and flat). These results suggest that almost all humans have some innate aptitude for absolute pitch recognition—though other factors may enhance or limit the level of that aptitude. Also, the results' conjunction with the aforementioned chronological observations suggests that early to mid-childhood exposure to environments whose interpretation depends on pitch is a developmental "trigger" for whatever aptitude an individual possesses.

Vestibular system

In our vestibular system, neurons are undeveloped at neuronal birth and mature during the critical period of the first 2–3 postnatal weeks. Hence, disruption of maturation during this period can cause changes in normal balance and movement through space. Animals with abnormal vestibular development tend to have irregular motor skills. Studies have consistently shown that animals with genetic vestibular deficiencies during this critical period have altered vestibular phenotypes, most likely as a result of insufficient input from the semicircular canals and dopaminergic abnormalities. Moreover, exposure to abnormal vestibular stimuli during the critical period is associated with irregular motor development. Children with hypofunctioning vestibular receptors frequently have delayed motor development. The results of the studies done on ferrets and rats reinforced the idea that the vestibular system is very important to motor development during the initial neonatal period. If the vestibular receptors are present during the initial six months to a year when the infant is learning to sit and stand, then the child may develop motor control and balance normally.

The vestibulo-ocular reflex (VOR) is a reflex eye movement that stabilizes images on the retina during head movement. It produces an eye movement in the direction opposite to head movement, thus preserving the image on the center of the visual field. Studies in fish and amphibians revealed a sensitivity in their VOR. They launched into space flight for 9–10, some with developing VORs and others with already developed reflexes. The fish with developing reflexes developed an upward bend in their tails. The altered gravity resulted in a shift of orientation. Those who were already matured with the reflex were insensitive to the microgravity exposure.

Memory

Recent studies also support the possibility of a critical period for the development of neurons that mediate memory processing. Experimental evidence supports the notion that young neurons in the adult dentate gyrus have a critical period (about 1–3 weeks after neuronal birth) during which they are integral to memory formation. Although the exact reasoning behind this observation is uncertain, studies suggest that the functional properties of neurons at this age make them most appropriate for this purpose; these neurons: (1) Remain hyperactive during the formation of memories; (2) are more excitable; and (3) More easily depolarizable due to GABAergic effects. It is also possible that hyperplasticity makes the neurons more useful in memory formation. If these young neurons had more plasticity than adult neurons in the same context, they could be more influential in smaller numbers. The role of these neurons in the adult dentate gyrus in memory processing is further supported by the fact that behavioral experiments have shown that an intact dentate gyrus is integral to hippocampal memory formation. It is speculated that the dentate gyrus acts as a relay station for information relating to memory storage. The likelihood of a critical period could change the way we view memory processing because it would ultimately mean that the collection of neurons present is constantly being replenished as new neurons replace old ones. If a critical period does indeed exist, this could possibly mean that: (1) Diverse populations of neurons that represent events occurring soon after one another may connect those events temporally in the memory formation and processing; or (2) these different populations of neurons may distinguish between similar events, independent of temporal position; or (3) separate populations may mediate the formation of new memories when the same events occur frequently.

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Malleability of intelligence

From Wikipedia, the free encyclopedia

Malleability of intelligence describes the processes by which intelligence can increase or decrease over time and is not static. These changes may come as a result of genetics, pharmacological factors, psychological factors, behavior, or environmental conditions. Malleable intelligence may refer to changes in cognitive skills, memory, reasoning, or muscle memory related motor skills. In general, the majority of changes in human intelligence occur at either the onset of development, during the critical period, or during old age (see neuroplasticity).

Charles Spearman, who coined the general intelligence factor "g", described intelligence as one's ability to adapt to his environment with a set of useful skills including reasoning and understanding patterns and relationships. He believed individuals highly developed in one intellectual ability tended to be highly developed at other intellectual abilities. A more intelligent individual was thought to be able to more easily "accommodate" experiences into existing cognitive structures to develop structures more compatible with environmental stimuli.

In general, intelligence is thought to be attributed to both genetic and environmental factors, but the extent to which each plays a key role is highly disputed. Studies of identical and non-identical twins raised separately and together show a strong correlation between child IQ and socio-economic level of the parents. Children raised in lower-class families tend to score lower on intelligence tests when compared to children raised in both middle and upper-class families. However, there is no difference in intelligence scores between children raised in middle versus upper-class families.

Definitions

  • Intelligence: a very general capability that, among other things, involves the ability to reason, plan, solve problems, think abstractly, comprehend complex ideas, learn quickly and learn from experience.
  • Critical period: a restricted developmental period during which the nervous system is particularly sensitive to the effects of experience.

Neuroscience basis

The biological basis of intelligence is founded in the degree of connectivity of neurons in the brain and the varying amounts of white and grey matter. Studies show that intelligence is positively correlated with total cerebral volume. While it is true that the number of neurons in the brain actually decreases throughout development, as neural connections grow and the pathways become more efficient, the supporting structures in the brain increase. This increase in supporting tissues, which include myelination, blood vessels, and glial cells, leads to an increase in overall brain size. When brain circumference and IQ were compared in 9 year olds, a positive correlation was found between the two. An increase of 2.87 IQ points occurred for each standard deviation increase in brain circumference.

Importance of critical period

The brain grows rapidly for the first five years of human development. At age five, the human brain is 90% of its total size. Then the brain finishes growing gradually until mid to late twenties. From start to finish, the brain increases in size by over 300% from birth. The critical period, defined as the beginning years of brain development, is essential to intellectual development, as the brain optimizes the overproduction of synapses present at birth. During the critical period, the neuronal pathways are refined based on which synapses are active and receiving transmission. It is a "use it or lose it" phenomenon.

Neural plasticity

Neural plasticity refers to any change in the structure of the neural network that forms the central nervous system. Neural plasticity is the neuronal basis for changes in how the mind works, including learning, the formation of memory, and changes in intelligence. One well-studied form of plasticity is Long-Term Potentiation (LTP). It refers to a change in neural connectivity as a result of high activation on both sides of a synaptic cleft. This change in neural connectivity allows information to be more easily processed, as the neural connection associated with that information becomes stronger through LTP. Other forms of plasticity involve the growth of new neurons, the growth of new connections between neurons, and the selective elimination of such connection, called "dendritic pruning".

Genetic factors of intelligence

Humans have varying degrees of neuroplasticity due to their genetic makeups, which affects their ability to adapt to conditions in their environments and effectively learn from experiences. The degree to which intelligence test scores can be linked to genetic heritability increases with age. There is presently no explanation for this puzzling result, but flaws in the testing methods are suspected. A study of Dutch twins concludes that intelligence of 5 year olds is 26% heritable, while the test scores of 12-year-olds is 64% heritable. Structurally, genetic influences explain 77–88% of the variance in the thickness of the mid-sagittal area of the corpus callosum, the volume of the caudate nucleus, and the volumes of the parietal and temporal lobes.

Pharmacological influence

Numerous pharmacological developments have been made to help organize neural circuitry for patients with learning disorders. The cholinergic and glutamatergic systems in the brain serve an important role in learning, memory, and the developmental organization of neuronal circuitry. These systems help to capitalize on the critical period and organize synaptic transmission. Autism and other learning disabilities have been targeted with drugs focusing on cholinergic and glutamatergic transmission. These drugs increase the amount of acetylcholine present in the brain by increasing the production of acetylcholine precursors, as well as inhibiting acetylcholine degradation by cholinesterases. By focusing on heightening the activity of this system, the brain's responsiveness to activity-dependent plasticity is improved. Specifically, glutamatergic drugs may reduce the threshold for LTP, promote more normal dendritic spine morphology, and retain a greater number of useful synaptic connections. Cholinergic drugs may reconnect the basal forebrain with the cortex and hippocampus, connections that are often disrupted in patients with learning disorders.

Psychological factors

Psychological factors and preconceived notions about intelligence can be as influential on intelligence as genetic makeup. Children with early chronic stress show impaired corticolimbic connectivity in development. Early chronic stress is defined as inconsistent or inadequate care-giving and disruption to early rearing environment. These children showed decreased cognitive function, especially in fluid cognition, or the ability to effectively utilize working memory. The lack of connectivity between the limbic system and the prefrontal cortex can be blamed for this deficiency.

Behavioral factors

In the study of malleable intelligence, behavioral factors are often the most intriguing because these are factors humans can seek to control. There are numerous behavioral factors that affect intellectual development and neural plasticity. The key is plasticity, which is caused by experience-driven electrical activation of neurons. This experience-driven activation causes axons to sprout new branches and develop new presynaptic terminals. These new branches often lead to greater mental processing in different areas.

Taking advantage of the critical period

As previously discussed, the critical period is a time of neural pruning and great intellectual development.

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