Intelligence: Definition, Measurement, and Theories

Capacity for higher mental processes like reasoning, remembering, understanding, problem-solving, and decision-making.
Working definition: reasoning, problem-solving, and dealing with changing environments.

Alfred Binet: Pioneering test for mental age.
Lewis Terman: Revised Binet's test (Stanford-Binet Intelligence Scale), assessing adults and children, model for IQ tests.
David Wechsler: Developed subtests, some non-verbal, providing scores for different cognitive abilities (e.g., verbal comprehension, perceptual reasoning, working memory, processing speed) and an overall IQ.
IQ (Intelligence Quotient): Reflects deviation from average performance for one's age group; average performance is $100$ .

Advantages: Standardized conditions, scores compared with norms.
Qualities of a Good Test: Statistical reliability (consistent results), statistical validity (appropriate interpretation and use of scores).
Effectiveness: Reasonably reliable, good predictor of academic success.
Limitations: Assess only some abilities, favor middle-class culture.

Both heredity and environment influence IQ and interact.
- Heredity: High correlation in IQs of identical twins raised separately, similarity between adopted children and biological parents.
- Environment: Higher IQ correlation among siblings sharing an environment, effects of environmental changes (e.g., adoption).
Average IQs differ across socioeconomic and ethnic groups due to educational opportunity, motivation, family support, and other environmental conditions.
Enriched environments can raise preschool children's IQs, though initial gains may decline, attitudes toward school may improve.

Psychometric Approach: Analyzes structure of intelligence via correlations.
- Charles Spearman: Concluded a general factor of mental ability ( $g$ ) and specific factors ( $s$ ).
- Raymond B. Cattell: Distinguished fluid intelligence (reasoning, problem-solving) and crystallized intelligence (specific knowledge).
- Modern theories describe a hierarchy: specific abilities in groups combining into a single general cognitive ability.
Information-Processing Model: Focuses on processes (attention flexibility/capacity, processing speed) underlying intelligent behavior.
Robert Sternberg's Triarchic Theory: Three types of intelligence: analytic, creative, and practical.
Howard Gardner's Multiple Intelligences: Biology equips for several independent intelligences: linguistic, logical-mathematical, spatial, musical, body-kinesthetic, intrapersonal, interpersonal, and naturalistic.

Giftedness: High IQs, generally healthier and more successful, but not necessarily geniuses.
Intellectual Disabilities: IQs below approximately $70$ as children, with functioning less than expected for their age.
- Causes: Some known; psychosocial intellectual disability has unknown genetic and environmental causes.
- Cognitive Characteristics: Slower information processing, fewer facts known, deficient in using mental strategies.
- Cognitive skills can be improved to some extent.