Determinants of Intelligence Lecture

Vocabulary flashcards summarising genetic and environmental determinants of intelligence, key research designs, disorders, and ethical considerations.

Intelligence

Cognitive capacity arising from the interaction of genetic inheritance (nature) and post-natal environment (nurture).

GENETIC & ENVIRONMENTAL INFLUENCES Of intelligence

●Genetic make-up (e.g. gene identified on chromosome 6 that codes for hormone receptor involved in learning & memory) 

 

●Genetic & chromosomal abnormalities (e.g. Down’s Syndrome) 

 

●Prenatal events (teratogens - drugs, poor nutrition, trauma, disease) 

 

●Postnatal events (e.g. lead exposure, maltreatment, environmental deprivation/enrichment, assistance, reward contingencies) 

 

●Planned interventions (e.g. Head Start program) 

 

●Family studies twin & adoption studies

Nature vs. Nurture

The debate over whether genetic factors (nature) or environmental factors (nurture) have a greater influence on human traits such as intelligence.

Heritability

Statistical estimate of how much variation in a trait within a population is due to genetic differences; for overall intelligence, ≈ 50 %.

Monozygotic (Identical) Twins

Twins originating from one fertilised egg that splits; share 100 % of genes and often a single placenta.

Dizygotic (Fraternal) Twins

Twins resulting from two separate eggs fertilised by two sperm; share about 50 % of segregating genes, like ordinary siblings.

Twin Studies

Research comparing identical and fraternal twins to estimate genetic versus environmental contributions to intelligence.

Average correlations in intelligence between identical twins raised together :

86 very high similarity

Adoption Studies

Research comparing adopted children’s IQ similarity to biological versus adoptive parents to separate genetic and environmental effects.

fraternal twins raised together:

62 moderate- high similarity

identical twins Reared apart

75 still higher than fraternal twins

Prenatal Environmental Factors

Influences before birth such as teratogens, poor maternal nutrition, trauma, or disease that can affect cognitive development.

Average correlations in intelligence between adopted child and biological parent

= 0.31 (moderate).

Postnatal Environmental Factors

After-birth influences like lead exposure, maltreatment, deprivation, enrichment, assistance, and reward contingencies that impact IQ.

Average correlations in intelligence between adopted child and Adoptive parent

.16 (low-moderate).

Planned Interventions

Structured programs (e.g., Head Start) designed to enrich early environments and boost cognitive development.

Environmental Enrichment

Provision of physical, sensory, and cognitive stimulation that supports neural growth and higher intellectual functioning.

Lead Neurotoxicity

Exposure to lead, a neurotoxin that can damage developing brains and lower intelligence.

Positive Environmental effects o intelligent

●prevention of exposure to adverse agents
●physical/sensory stimulation, environmental enrichment
 ●warmth, parental involvement
 ●modelling/rewards for intellectual effort
 ●scaffolding, assistance with problem-solving 

 

-> positive effects on intelligence

 

Scaffolding

Supportive assistance provided to children during problem-solving that fosters higher-level cognitive skills.

Intellectual Disability

Condition marked by IQ below 70 and significant deficits in adaptive functioning beginning in childhood.

Adaptive Functioning

Everyday skills in communication, social interaction, and daily living required for independent life; must be impaired for diagnosis of intellectual disability.

Severe Intellectual Disability

A classification applied to roughly 10 % of individuals with intellectual disabilities, indicating profound cognitive and functional limitations.

Down Syndrome

Genetic disorder (trisomy 21) characterized by distinct facial features and intellectual impairment.

Phenylketonuria (PKU)

Inherited disorder in which lack of an enzyme prevents proper metabolism of phenylalanine, potentially causing intellectual disability unless managed by diet.

Genetic Abnormality

Any deviation in chromosome number or gene structure (e.g., Down syndrome) that can affect intelligence.

Teratogen

Any prenatal agent (drug, toxin, disease) capable of causing congenital defects or cognitive impairment.

Gene on Chromosome 6

Identified genetic locus coding for a hormone receptor implicated in learning and memory processes.

Giftedness

Exceptional intellectual ability, typically indicated by an IQ above 130, often requiring tailored educational enrichment.

Early Identification

The process of detecting cognitive risks or gifts in childhood to enable targeted interventions that optimise intellectual outcomes.

Ethical Caution

Guideline to avoid deterministic labelling; genetic propensity influences but does not dictate intellectual destiny.