Intelligence

Brain development

The brain requires 60% of the body's energy

The Curse of Eve

• giant human brains required a larger baby head

• bipedalism required a narrower pelvis

• creates “Obstetrics Dilemma”

Obstetrics Dilemma

Human childbirth is longer, more painful, and historically more dangerous due to the evolutionary trade-offs between infant brain size, infant dependency period, female pelvic width, and maternal mortality (1% per birth)

Runaway sexual selection theory

The theory that the insatiable need for more intelligent mates led to the evolution of giant human brains.

Social brain hypothesis

The theory that big brains evolved as a way to navigate complex social lives.

Intelligence

The ability to solve novel problems and learn from experience.

IQ

A measure of individual differences in general cognitive ability, originally developed to identify cognitive delays among children in school.

• mean of 100, SD of 15

• mean of children in school is 115

Who’s Goddard?

One of the first to measure intelligence, and used it discriminatorily towards US immigrants

Who are Binet & Simon

Developed the first intelligence test to identify children who needed remedial education

• measured aptitude apart from achievement

Who’s Terman?

Developed modern IQ test

Ratio IQ

A child's "mental age" divided by their chronological age, multiplied by 100.

• had to abandon this age-based calc in order to measure difference in intelligence between adults

Deviation IQ

A person's test score divided by the average test score of the same age group, multiplied by 100.

• used today

Intelligence tests

Used to measure tasks that correlate with intelligence, not intelligence itself.

• typically used to assess cognitive abilities

most used intelligence tests today

• Wechsler Adult Intelligence Scale (WAIS)

• Wechsler Intelligence Scale for Children (WISC)

Is IQ a valid measure

• yes, it predicts what we would expect it to predict

• correlates +vely with academic grades and income

• correlates -vely with arrests and drug and alcohol use

Two-factor theory of intelligence

• spearman’s theory that every task requires a combo of:

  1) an overall single general ability (g) and

  2) skills that are specific to the task (s)

Thurstone on the hierarchy of abilities

• argues for a few primary mental abilities that were stable and independent

Middle-level abilities

Abilities that lie between specific and general mental abilities with regard to intelligence.

A three-level hierarchy

Correlations between scores on different mental ability tests are best described in a three-level hierarchy consisting of spearman’s general factor (g) and specific factors (s), and then in between is Thurstone’s group of factors (m)

2 approaches to the middle-level abilities

1) data-based approach

2) theory-based approach

data based approach

connect intelligence test performance to clusters

• includes crystallized and fluid intelligence

Crystallized intelligence

The ability to retain and use knowledge acquired through experience (facts, vocab, trivia).

Fluid intelligence

The ability to see abstract relationships and draw logical inferences (problem solving)

Theory based approach

Broadly surveys human abilities and then determines which one’s intelligence tests do/don’t measure

• includes analytical, creative, and practical intelligence

Analytical intelligence

finding correct answer to a defined problem

Creative intelligence

finding novel solutions and choosing which to apply

Practical intelligence

implementing solutions in everyday settings

Emotional intelligence

The ability to identify, describe, predict, and manage one's own emotions and those of others.

People with higher EQ…

• are happier

• report greater life satisfaction

• are physically and mentally healthier

• have better social skills (more socially competent)

• have better relationships

• more likely to be promoted

Heritability

how much of observed differences between people can be attributed to genes

Heritability coefficient (h²)

statistic that describes the proportion of the difference between 2+ people’s IQ scores that can be explained by differences in their genes

Flynn effect

The average intelligence test score rises about 0.3% every year.

SES

One of the best predictors of intelligence is socioeconomic status.

Education

The correlation between formal education and intelligence is large, but education may improve test-taking ability rather than general cognitive ability.

Nature-nurture distinction

Nature and nurture have a combined influence on IQ, interacting in complex ways.

Mensa

largest international high IQ society

Intellectual Developmental Disorder

A classification based on IQ levels; mild, moderate, severe, and profound.

Mild

• IQ 50-69

• 80-85% of cases

• “educable” level (can benefit from schooling)

• Can lead independent lives

• Maintain unskilled or semiskilled jobs

Moderate

• IQ 35-49

• 10% of cases

• Deficits in language development and play

• Can care for themselves

• Benefit from vocational training

• May be able to work under supervision

Severe

• IQ 20-34

• 3-4% of cases

• Basic motor and communication deficits in infancy

• Require careful supervision and can perform basic work tasks

• Rarely able to live independently

Profound

• IQ <20

• 1-2% of cases; 70% male

• Noticeable at birth/early infancy

• Need structured environment and one-on-one help from caregiver

Gender differences

Females and males have the same average IQ, but it’s perceived that males have higher IQ b/c their IQ score distribution is more spread out (SD larger)

Culture, Race, and IQ

• Terman involved in Binet & Simon’s work to produce Standford-Binet intelligence scale

• his claims of intelligence were racist

• Between-group differences in IQ scores exist, but the causes are difficult to pinpoint and may include factors such as nutrition, socioeconomic status, education, cultural specificity of IQ tests, and stereotype threat.

• between-group diff tend to be less than within-group diff

Self-Fulfilling Prophecy

The more you think about not doing something, the more likely you are to do it.

Stereotype Threat

• fear of confirming negative beliefs that others may hold about their group

• the more you think about doing something, the more likely you’ll do it (skiing analogy)

Performance vs Ability

Differences in performance do not necessarily reflect differences in ability.

Environmental Influence on Intelligence

Environmental differences can influence intelligence, such as chronic illness, poor medical care, and exposure to toxic chemicals.

Socioeconomic Status (SES) and Intelligence

Differences in SES can influence intelligence, with lower SES often associated with poorer development and educational opportunities.

Genetic Explanation

The genetic explanation for intelligence is not well-supported, as shown by adoption studies and bi-racial children.

Improving Intelligence in Children

Strategies such as feeding children polyunsaturated fatty acids, early educational interventions, interactive reading and conversing, and preschool can help improve intelligence in children.

Improving Intelligence in Individuals

Mental exercises and cognitive enhancers can provide short-term benefits for improving intelligence, but caution should be taken regarding side effects.

Rest and Brain Health

Rest is important for maintaining brain health.