Intelligence, Cognition, and Language

Sensory Capacity (Galton, 1884): Intelligence linked to sensory sharpness; weak correlation with traditional measures and varies within individuals.
Abstract Thinking (Binet and Simon): Ability to form abstract concepts, learn, and adapt; foundation for modern IQ tests.
General Intelligence (Spearman): Proposed an overarching $g$ factor (general intelligence) and domain-specific $s$ factors based on positive subtest correlations ( $r \approx 0.2 - 0.3$ ).
Fluid vs. Crystallized Intelligence (Cattell & Horn):
- Fluid Intelligence: Logical thinking, learning, and novel problem solving (inductive and deductive reasoning); declines with age.
- Crystallized Intelligence: Accumulated knowledge and vocabulary; remains stable across lifespan.
Multiple Intelligences (Gardner): Proposes $8$ distinct modalities (Linguistic, Logico-mathematical, Spatial, Musical, Bodily-kinesthetic, Interpersonal, Intrapersonal, Naturalistic).
Triarchic Theory (Sternberg): Divides intelligence into Analytic ("book smarts"), Practical ("street smarts"), and Creative domains.

Brain Correlates:
- Positive correlation with brain volume ( $r \approx +0.3$ ) and working memory ( $r \approx +0.5$ ).
- High prefrontal cortex activation in $g$ -loaded tasks; lower overall brain activity in high scorers during task learning (neural efficiency).
- Inverse correlation with reaction time ( $r \approx -0.3$ ).
Testing Instruments: Includes WAIS-IV, WISC-IV, WPPSI-III, SB5, WJ-Cog-III, and KAIT, evaluating verbal and perceptual-motor scales.
Age-Based IQ (Stern, 1912): Computed as: $IQ = \frac{MA}{CA} \times 100$ where $MA$ is Mental Age and $CA$ is Chronological Age. Invalid for adults due to intellectual stabilization around age $16$ .
Deviation IQ: Standardized normal curve comparison where median $IQ = 100$ within age cohorts.

Intellectual Disability: Characterized by $IQ < 70$ , onset before adulthood, and deficits in adaptive functioning. Over $85\%$ of cases are mild; predominantly affects males due to X-linked recessive genetics (e.g., Fragile X syndrome, Down syndrome).
Giftedness and Eminence: Giftedness defined as $IQ \ge 130$ ("Terman's Termites"). Profound giftedness ( $IQ \ge 180$ ) carries higher social isolation and mental illness risk. Eminence requires high IQ, creativity, and motivation (Renzulli).
Culture-Fair Testing: Raven's Progressive Matrices minimizes language and cultural bias through abstract pattern completion.

Predictive Limitations: Modest correlations with academic success ( $r \approx 0.5$ ), job performance ( $r \approx 0.1 - 0.5$ ), and socioeconomic status ( $r \approx 0.3$ ). IQ prediction levels off above moderate thresholds.

Genetic Contribution: Heritability estimates range between $50\%$ and $70\%$ . Correlations: identical twins reared together ( $r \approx 0.75$ ) vs. reared apart ( $r \approx 0.65$ ); fraternal twins ( $r \approx 0.35$ ); siblings ( $r \approx 0.50$ ); cousins ( $r \approx 0.15$ ).

Environmental Factors: Influenced by poverty, expectancy effects, and home enrichment.
Flynn Effect: Population average IQ increases by approximately $3$ points per decade.
Group Differences:
- Gender: Equal average IQ, but males show greater variability at extremes. Females excel in verbal tasks and emotion recognition; males in mental rotation and spatial reasoning.
- Ethnicity: Differences disappear when controlling for socioeconomic status (Kamin's cornfield analogy).

Creativity: Relies on divergent thinking ("outside-the-box") and convergent thinking; correlates weakly with IQ ( $r \approx 0.25$ ).
Emotional Intelligence (EQ / Goleman): Ability to perceive, integrate, understand, and manage emotions (measured via MEIS); uncorrelated with IQ and job performance.

Cognitive Economy & Heuristics: Mind minimizes effort using shortcuts.
- Representativeness Heuristic: Judging probability by similarity to prototypes, ignoring base rate information.
- Availability Heuristic: Estimating likelihood based on memory accessibility.
Decision Making: System $1$ (intuitive/fast) vs. System $2$ (deliberate/rational). Subject to the Framing Effect (preferences depend on positive vs. negative wording).
Problem Solving: Methods include heuristics, sub-problem breakdown, analogies, and algorithms. Blocked by mental sets and functional fixedness.

Language Structure: Phonemes (sound units), Morphemes (meaningful units), Syntax (sentence rules), Semantics (deep meaning), and Extralinguistic information.
Developmental Stages: Prenatal, Cooing (birth– $6$ months; universal adaptability), Babbling ( $6$ – $12$ months), Holophrasic ( $12$ – $18$ months; one-word), Telegraphic ( $18$ months– $4$ years; content words), Grammar ( $4$ – $6$ years), and Meta-linguistic ( $6+$ years).
Theories: Behaviorist (Skinner; conditioning/imitation), Nativist (Chomsky; Language Acquisition Device - LAD), Interactionist (Social Pragmatics; sensitive periods), Cognitive Processing.
Linguistic Relativity: Language shapes and influences thought (Sapir-Whorf hypothesis).
Reading Processing: Dual-route reading via Whole Word Recognition (familiar words) and Phonetic Decomposition / Phonics (new words). Speech constrained by Stroop Effect.

Speed Reading: Physical constraints include saccadic movement ( $30\,ms$ ) and fixation ( $250\,ms$ ); speeds exceeding $400$ words per minute impair comprehension.