Unit 2.8: Intelligence and Achievement

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
• Intelligence is largely inherited and relatively stable

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.

Alfred Binet (1904)

• 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
• Created the Intelligence Quotient (IQ) formula
• Believed intelligence was largely inherited
• IQ became widely used for educational placement

\(\text{IQ} = \frac{\text{Mental Age}}{\text{Chronological Age}} \times 100\)

Example Calculation:

• A 10-year-old who performs at a 12-year-old level: IQ = (12/10) × 100 = 120
• A 10-year-old who performs at a 10-year-old level: IQ = (10/10) × 100 = 100
• A 10-year-old who performs at an 8-year-old level: IQ = (8/10) × 100 = 80

Wechsler Scales (Most Widely Used Today)

• WAIS (Wechsler Adult Intelligence Scale) — for adults 16+
• WISC (Wechsler Intelligence Scale for Children) — for ages 6-16
• WPPSI (Wechsler Preschool and Primary Scale) — for ages 2-7

Features: Separate scores for verbal and performance abilities; uses statistical norms instead of mental age ratio

IQ Score Distribution:

Modern IQ scores follow a normal distribution (bell curve):

• Mean (average) = 100
• Standard deviation = 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
• Effect disappears when stereotype threat is removed

Classic Research Example:

Black students performed worse on tests when reminded of their race beforehand, but performed equally well as white students when race was not mentioned — demonstrating that the performance gap was due to stereotype threat, not ability differences.

Critical Facts:

• Within-group variation > Between-group variation: IQ scores vary MORE within any group than between different groups
• Environmental factors explain differences: Socioeconomic status, education quality, healthcare, nutrition, discrimination
• No genetic basis: There is NO evidence that group differences reflect genetic differences in intelligence
• Scores are malleable: When environmental factors are equalized, group differences disappear