Chapter 12 — Intelligence (Comprehensive Bullet-Point Notes)

Learning Outcomes

• 12.1 Describe the nature of intelligence

• 12.2 Explain how intelligence is measured

• 12.3 Distinguish among different approaches to intelligence

• 12.4 Discuss the extent to which intelligence is inherited or learned

Conceptual Overview of “Intelligence”

• Definition: application of cognitive skills & knowledge to learn, solve problems, reach culturally-valued goals

• Properties - Multifaceted (expressed in many domains)

  • Functional (goal-directed, adaptive)

  • Culturally shaped/defined

• Practical vs academic vs social facets recognised by laypersons

• Intelligence = “capacity for goal-directed adaptive behaviour” (Sternberg & Salter, 1982)

• Evolutionary view: solves problems of adaptation ⇒ survival, reproduction

• Cognitive view: “applied cognition” (use of cognitive skills to solve problems)

• Provisional working definition (Gardner 1983): see bullet 1 above

Opening Case: The Tao Family (Real-World Illustration)

• Parents: Billy (paediatrician) & Grace (honours maths/physics); migrated from HK → Adelaide, 1972

• Three sons demonstrate extremes of intellectual functioning - Terry Tao (“Mozart of maths”): mastered primary curriculum in kindergarten; uni lectures by 9; BSc 16, MSc 17, PhD Princeton 20; youngest UC Berkeley full professor (24); numerous awards

  • Nigel Tao: IQ ~ 180; bronze medals in 2 International Mathematical Olympiads; Google software engineer

  • Trevor Tao: diagnosed autism @ 2 (late speech, cue cards, repetitive behaviour, routine rigidity); integrated into regular school; PhD applied maths; represented Australia at Chess & Math Olympiads; musical savant—played 1st movement of Dvořák’s “New World” from memory at 11 (orchestral work, never written for piano)

• Raises key questions: - What is intelligence?

  • Measurement accuracy & cultural neutrality?

  • One general trait vs multiple kinds?

  • Nature vs nurture? (parents both talented in maths; enriched environment)

Early History & Pioneers

• Sir Francis Galton (1822-1911) - Darwin’s cousin; aristocrat

  • First systematic mental testing lab (London 1884 exposition); sensory, motor, reaction-time tasks for 3 pence/subject; ~10 000 participants

  • Found poor correlations with social class ⇒ sensory tasks NOT good proxies

  • Statistical legacy: correlation coefficient

• Alfred Binet (1857-1911) - Goal: identify French schoolchildren needing special help

  • Binet–Simon scale 1905; tasks from simple→complex; concept of Mental Age (MA)

• Lewis Terman (Stanford, 1916) - Stanford–Binet; introduced Intelligence Quotient formula IQ = (MA/CA) * 100

  • Extended purpose from school placement → broader ability prediction

• Group Tests WW-I - Army Alpha (literate) & Beta (illiterate/non-English); > 1.7 million tested

  • Cultural & linguistic bias (e.g., immigrants)

  • “Dictation test” in White Australia Policy era analogous bias

Contemporary Major IQ Scales

• Stanford–Binet 5 (Roid & Barram 2004) - Age 2 → 85+

  • Based on Cattell–Horn Gf-Gc (measures fluid reasoning, knowledge, quantitative reasoning, visual-spatial processing, working memory)

• Wechsler Family - WAIS-IV (2008) adults, WISC-V (2014) children 16↓, upcoming WAIS-V

  • Indexes

  • Verbal Comprehension (VCI)

  • Perceptual Reasoning (PRI)

  • Working Memory (WMI)

  • Processing Speed (PSI)

  • Optional General Ability Index (GAI = VCI+PRI composite)

  • Subtests examples: Similarities, Vocabulary, Information, Block Design, Matrix Reasoning, Digit Span, Symbol Search, etc.

  • Abandoned MA; IQ = position on age-normed normal curve (mean 100, SD 15)

• Frequency Distribution - Bell curve; 68 % between 85-115; 2 % < 70 (intellectual disability threshold); 2 % > 130 (gifted)

Reliability & Validity

• IQ to school grades r ~ .60–.70 (comparable to height–weight)

• Test–retest reliability high (WISC stability across 3 yrs childhood)

• Validity goal-dependent; must supplement with other measures

• Criticisms - Limited theoretical basis; ignore practical intelligence, creativity, socio-emotional skill

  • Cultural bias; favour white middle-class Western learning modes

  • Speed emphasis may penalise cultures valuing deliberation

• Culture-Free vs Culture-Fair attempts largely unsuccessful; cultural influence persists

Extremes of Intelligence

• Intellectual Disability - Definition: IQ < 70 + significant adaptive deficits onset < 18 yrs

  • Only ~10 % severe/profound (< 50)

  • Causes

  • Genetic: Down syndrome (trisomy 21), PKU (diet-modifiable)

  • Teratogens: alcohol (Fetal Alcohol Syndrome), cocaine

  • Psychosocial: poverty, maltreatment, low maternal education

  • Stats: 6.5 % of Australians with disability have ID; 190 000 kids 0-14 (4.3 %)

• Giftedness - Often IQ > 130; but includes musical, athletic, social talents

  • Terman’s “Termites” longitudinal: high IQ ⇒ average up adjustment, success; later dissatisfaction if expectations high

  • Australian data: IQ 160+ children risk social isolation; need enrichment

  • Cultural conceptions: Maori & Aboriginal giftedness includes linguistic, spatial, naturalistic, spiritual domains (Gibson & Vialle 2020)

  • Programs like Moorditj Kulungar highlight hidden Aboriginal giftedness

• Creativity - Defined: ability to produce valued novel outcomes

  • Moderately correlated with IQ; divergent thinking a measure (e.g., alternate uses for paperclip)

  • Personality correlates: high energy, risk-taking, intrinsic task engagement

  • Domain-specificity evidence (Baer 2012)

Approaches to Intelligence

Psychometric (Structure-of-Intellect)

• Uses factor analysis to see which abilities cluster

• Spearman Two-Factor - g general factor

  • s specific factors (e.g., verbal, numerical)

• Thurstone: 7 primary mental abilities (word fluency, reasoning, etc.)

• Carroll Three-Stratum - Stratum III: general (g)

  • Stratum II: broad abilities (fluid Gf, crystallised Gc, visual, auditory, memory, processing speed, reaction/decision speed)

  • Stratum I: 60+ narrow abilities

• Cattell–Horn Gf-Gc - Fluid (Gf): reasoning, pattern-analogy, novel problem solving

  • Crystallised (Gc): acquired knowledge, vocabulary

  • Seven specific factors (STM, LTM, Gv, Ga, Gs, Gt, quantitative QK)

  • Developmental trajectories (Gc up to ~60; Gf down after mid-20s)

• CHC (Cattell–Horn–Carroll): integrative modern model; basis of recent test revisions

Information-Processing (Cognitive)

• Focus on “how” intelligence operates

• Key variables - Processing speed (letter pair tasks; AA vs Aa reaction time)

  • Knowledge base (amount, structure, accessibility; expert schemas)

  • Strategy acquisition & application (mnemonics, problem-solving heuristics)

• Differences in these predict IQ & achievement; changes with age (speed peaks young; knowledge base grows)

Multifactor / Functional Theories

• Sternberg Triarchic - Analytical (componential) — academic / IQ-type

  • Creative (experiential) — novel solutions, insight

  • Practical (contextual) — “street smarts”, adapt-shape-select environments

  • Underpinned by meta-components (planning, monitoring), performance components (executing), knowledge-acquisition components (learning)

• Gardner Multiple Intelligences - Eight core: Linguistic, Logical/Mathematical, Spatial, Musical, Bodily/Kinaesthetic, Interpersonal, Intrapersonal, Naturalistic

  • Possible additions: Spiritual / Existential

  • Criteria: neurological modularity, existence of prodigies/savants, distinct developmental courses

  • Emotional intelligence ~ Inter- & Intra-personal domains

• Emotional Intelligence (Mayer, Salovey, Goleman) - Abilities: perceive, use, understand, manage emotions

  • Linked to leadership (Australian executive study), academic success, life satisfaction; measurement issues (self-report vs performance)

Measurement Ethics & Cultural Issues

• APS apology 2016 for past misuse of Western tests with Indigenous Australians

• Koori IQ Test (Wilson-Miller 1982) illustrates cultural loading

• NAPLAN: national literacy/numeracy; concerns “teach to test” & school marketing bias

• Australian Early Development Census includes social, physical, emotional domains acknowledging broader influences

• Work & forensic contexts: question of IQ necessity for competent judgement (ethical dilemmas)

Heredity vs Environment

Evidence from Correlations

• Heritability of IQ ~ .45 childhood to .75 adulthood (Western middle-class)

• Genes identified (chromosome 6 hormone receptor; chromosome 4 variants) each explain only 1-3 % variance

Environmental Risk / Enrichment

• Sameroff family risk index: cumulative risks (low maternal education, mental illness, minority status, large family) correlate r ~ .70 with IQ at 4 & 13

• Longitudinal Australian data: early aggression/restlessness + marital instability double delinquency risk @ 14 (Bor et al., 2004); SES to poorer learning behaviours; teacher expectations bias

• Remote Indigenous children: lower literacy linked to remoteness, language, health, SES; yet superior visuospatial & working-memory strengths suggest need for strength-based pedagogy

• Enriched animal environments increase brain mass & learning to analogous human effects

Caveats in Heritability Interpretation

• Heritability stats assume random mating/environments; assortative mating & niche-picking inflate estimates

• Coefficients population-specific; twin studies mostly middle-class; variation wider to heritability decrease

Group Differences

• Historical misuse: 1961 NSW board blamed Aboriginal retention on low IQ; tests culturally biased

• Flynn Effect: average IQ increased ~3 pts/decade in industrial nations; environment (modernisation, complexity, nutrition, test design) key

• Analogy: average male height increased 11 cm 1913→2004; heritability still high within cohorts; shift itself environmental

Practical & Professional Implications

• Psychologists must master administration/interpretation (Psychology Board of Australia requirement; WAIS, WISC)

• Testing uses: educational placement (gifted, disability), clinical diagnosis, TBI assessment, personnel selection (ethical caution)

• Admissions/employment decisions should triangulate IQ with motivation, social skills, task-specific samples; avoid sole reliance

• When designing assessments cross-culturally: tailor to local values, translate cautiously, incorporate culturally valid constructs

• Sternberg et al. 2021—10 counter-assumptions for gifted identification (comprehensive assessments, gene–environment transactions, transformational vs transactional giftedness, cultural views, responsible non-verbal tests, etc.)

Ethical, Philosophical & Societal Reflections

• Intelligence partly match between person & historical context (e.g., modern media careers)

• Debates around IQ, genetics, race coloured by social history; need open, careful, sensitive research

• APS apology highlights responsibility to avoid diagnostic/assessment harm to marginalised groups

• Ongoing question: relationship between intelligence & wisdom; overlap or distinct constructs?

Key Formulas & Statistics

• IQ = (MA/CA) * 100 original ratio

• g–task PET activation: dorsolateral prefrontal cortex (qualitative)

• Flynn effect: Change in IQ ~ 3 points/decade

Apply & Discuss Prompts (Condensed)

• Relationship between intelligence & wisdom

• Comparing psychological yardsticks across domains (chef vs electrician vs doctor)

• Impact of language/culture on Koori IQ Test performance

• Creativity domain-specificity; can one be creative but not “intelligent” or vice versa?

• Emotional intelligence versus general intelligence relationship hypothesis

Interim Summaries (Consolidated)

• Intelligence: multifaceted, functional, culturally bound

• Tests: psychometric tools; high reliability/validity for scholastic prediction; culturally limited

• Approaches: psychometric (g + factors), cognitive (process variables), practical/multiple (triarchic, MI)

• Nature vs nurture: both significant; genes stronger within-group, environment drives between-group & temporal shifts

Concluding Synthesis for Exam Prep

• Know definitions, formulas, test structures, factor models

• Relate real-world cases (Tao family, Army tests, NAPLAN, Indigenous contexts)

• Be able to critique tests re: validity, reliability, cultural fairness

• Understand multifactor theories & evidence supporting/criticising each

• Anticipate essay Qs on nature-nurture, giftedness, intelligence measurement ethics, and modern expansions (emotional, practical, multiple intelligences)