Intelligence and Achievement — AP Psychology Study Notes

Core Idea:

• People who perform well on one type of mental task tend to perform well on other types
• This correlation across different tasks suggests one underlying general ability
• While people have specific abilities (s factors), g is the foundation
• Genetic and environmental influences both contribute to differences in cognitive performance. Stability and heritability depend on the population, age, context and measurement; heritability does not assign a genetic percentage to one person or make ability unchangeable.

Example:

A student who excels in mathematics usually also performs well in verbal reasoning, science, and spatial tasks because they all draw on general intelligence (g).

The Eight Intelligences:

• Linguistic: Mastery of language, writing, and communication (poets, journalists)
• Logical-Mathematical: Logical analysis and mathematical problem-solving (scientists, programmers)
• Spatial: Visualizing and manipulating objects in space (architects, surgeons)
• Musical: Sensitivity to rhythm, pitch, and tone (composers, performers)
• Bodily-Kinesthetic: Control of body movements and handling objects (athletes, dancers)
• Interpersonal: Understanding and interacting with others (counselors, politicians)
• Intrapersonal: Self-awareness of feelings and motivations (philosophers)
• Naturalistic: Recognition of natural elements (biologists, environmentalists)

Key Point:

A brilliant musician might struggle with mathematics, and an exceptional athlete might have average linguistic abilities. Gardner's theory explains why people can be "smart" in different ways.

Three Types of Intelligence:

Example:

A student might excel on standardized tests (analytical), design innovative science projects (creative), and know exactly how to persuade teammates to collaborate (practical). Sternberg's theory explains why some people are "book smart" but struggle in real-world situations, or vice versa.

Binet and Simon: work commissioned in 1904, first scale in 1905

• Developed the first intelligence test to identify French students needing special education
• Introduced the concept of mental age — the age level of mental ability
• Did NOT believe intelligence was fixed or hereditary
• Believed intelligence could be improved through education

Lewis Terman - Stanford-Binet (1916)

• Adapted Binet's test for American children
• Stern proposed an age-ratio intelligence quotient; Terman’s Stanford–Binet revision helped popularize IQ scoring. The ratio approach belongs to the history of testing, not modern age-normed scoring.
• Believed intelligence was largely inherited
• IQ became widely used for educational placement

Example Calculation:

• A 10-year-old performing at the historical 12-year mental-age level: $\text{IQ}=\frac{12}{10}\times 100=120$.
• A 10-year-old performing at the historical 10-year mental-age level: $\text{IQ}=\frac{10}{10}\times 100=100$.
• A 10-year-old performing at the historical 8-year mental-age level: $\text{IQ}=\frac{8}{10}\times 100=80$.

Wechsler Scales (Most Widely Used Today)

• WAIS: An adult intelligence-scale family, including the current U.S. WAIS-5; its age range begins at 16 years. Edition and regional norms matter.
• WISC-V: The U.S. child scale covers ages 6 years 0 months through 16 years 11 months.
• WPPSI-IV: The U.S. preschool/primary scale covers ages 2 years 6 months through 7 years 7 months.

Features: Modern editions report overall and domain/index scores using age-based norms. The older verbal-versus-performance split does not describe every current edition’s score structure.

IQ Score Distribution:

Many widely used IQ scales are normed to an approximately normal distribution within an age group, commonly with $\mu =100$ and $\sigma =15$. The percentages below are normal-model approximations, not an exact claim about every test or real sample.

• $\mu =100$
• $\sigma =15$
• 68% of people score between 85-115
• 95% of people score between 70-130
• 99.7% of people score between 55-145

Requirements:

• Same instructions for all test-takers
• Same time limits and testing conditions
• Same scoring procedures
• Comparison to norm group (representative sample establishing average performance)
• Regular re-norming to maintain accuracy over time

Types of Reliability:

• Test-Retest Reliability: Same person gets similar scores when taking the test at different times
• Split-Half Reliability: Two equivalent halves of the test yield similar scores (internal consistency)
• Inter-Rater Reliability: Different scorers give the same score to the same test

Types of Validity:

• Construct Validity: Test accurately measures the theoretical concept (e.g., intelligence, not just memorization)
• Predictive Validity: Test scores predict future performance or behavior (e.g., IQ predicting academic success)
• Content Validity: Test items comprehensively cover the domain being measured

Proposed Explanations:

• Better nutrition and healthcare: Improved prenatal and childhood health supports brain development
• More education: Increased years of schooling and educational quality
• Cognitively demanding jobs: Modern work requires more abstract thinking
• Test familiarity: Greater exposure to standardized testing formats
• Smaller families: More parental attention and resources per child
• Environmental complexity: Technology and media increase cognitive stimulation

Important Implication:

The Flynn Effect demonstrates that intelligence is NOT purely genetic or fixed. Environmental and societal factors play a significant role in intellectual development and test performance.

Sources of Bias:

• Language differences: Tests in dominant language disadvantage non-native speakers
• Cultural experiences: Test items assume specific cultural knowledge or experiences
• Test format familiarity: Some cultures have more exposure to standardized testing
• Values and priorities: Different cultures value different types of knowledge
• Socioeconomic factors: Poverty limits access to educational resources

Example:

A vocabulary question asking about "regatta" (a boat race) assumes familiarity with sailing culture, which is more common in affluent communities. Students from landlocked, low-income areas might miss this question despite having equal intelligence.

How It Works:

• Person becomes aware of negative stereotype about their group
• Fear of confirming the stereotype creates anxiety and stress
• Mental resources are diverted to managing anxiety rather than the test
• Performance decreases, ironically confirming the stereotype
• Reducing evaluative threat can improve performance in some settings, but effects vary and removing one cue does not guarantee elimination of a score difference.

Classic Research Example:

Classic experiments examined whether evaluative framing and stereotype-related cues could affect performance. Interpret effects within the studied design and sample. They do not show that all group differences are caused by a single cue or that any one intervention makes all groups perform identically.

Critical Facts:

• Group distributions overlap: A group average does not describe every member or determine an individual’s score. The extent of within-group variation and between-group differences depends on the sample, measure and context; neither alone establishes a cause.
• Environmental factors explain differences: Socioeconomic status, education quality, healthcare, nutrition, discrimination
• Do not infer causation from a group label: Test-score comparisons alone cannot separate inherited and environmental causes. Broad social categories are not measurements of an individual’s inherited cognitive potential.
• Scores can change: Educational and environmental changes can affect performance. It is too strong to claim that equalizing one set of measured conditions will always eliminate every observed difference.