Biological Psychology

Basic assumptions

• Characteristics should be heritable

• Characteristics should not be markedly influenced by the environment

Heritability of IQ
(Williams & Ceci, 1997)

• .86 for identical twins raised together

• .61 for fraternal twins raised together

Ethnic Differences in IQ

Dysgenesis hypothesis
(Herrnstein & Murray, 1994)

• Persons with lower IQs have more offspring than persons with higher IQs

– The cognitive gap will increase

The cognitive ability gap has actually decreased (Williams & Ceci, 1997)

Why has the cognitive gap decreased?

• Educational intervention programs (e.g., Head Start)

• Cognitive abilities are malleable

Poverty and IQ
(Dickens, Kane, & Schulze, 1995)

• Are ethnic minorities poor because they have low IQs?

• If all people had the same IQ and only non-cognitive variables were allowed to vary (e.g., parental SES, motivation), then the income distribution would resemble what we have now

Poverty and IQ
(Dickens, Kane, & Schulze, 1995)

• If non-cognitive variables (parental SES, motivation) were equated and only IQ scores were allowed to vary, there would be a more egalitarian income distribution

Success and IQ (Sternberg, 2000)

Blood Pressure
(Blascovich et al., 2001)

• Blood pressure and stereotype threat

– The discomfort persons feel when they are at risk of fulfilling a negative stereotype about their group)

High stereotype threat

• Study is on standardized test bias

• Test given to achieve a nationally representative sample

• Test developed by researchers from Stanford, Princeton, Michigan

Low stereotype threat

• Study to develop a culturally unbiased test

• Test given to demonstrate its fairness

• Test developed by researchers from Tulane, Howard, Michigan

Stereotype threat x blood pressure

• Constant stereotype threat may result in chronic blood pressure changes

Sociobiology
(Tooby & Cosmides, 1990)

• The human mind is composed of psychological information-processing mechanisms that are shaped by natural selection

• These mechanisms address early human problems, such as the need to attract a mate, acquire a language, detect cheaters in social exchange, avoid predators

Sociobiology
(Tooby & Cosmides, 1990)

• Sufficient time has not elapsed to change the mental mechanisms that evolved in hunter-gatherer conditions in the Pleistocene era

– Some maladaptive behaviors may persist

Cultural selection
(Dawkins, 1976)

• Meme – unit of cultural selection

– Ideas, fashions, information, thoughts, theories, songs, pieces of art

• Analogous to gene

– Both make copies of themselves, mutations can occur in the copying process, both are differentially replicated or selected, both are in competition with others

– Genes can only be transmitted from parent to child, whereas parent-child is only one form of transmission of memes

Cultural selection
(Dawkins, 1976)

• Memes are selected because of their popularity, not necessarily because they contribute to biological fitness

• Infants adopt memes that are relevant in their particular cultural environment

Cultural change involves the selection of particular memes

• Memes can sometimes change the biological selection process

– Cultural rejection of aggression

• Is a biological basis of culture necessary?

– Do biology and culture become uncoupled at some point?

General criticisms of sociobiology

• Social Darwinism - social privilege is the result of evolutionary differences

• Observed patterns of behavior (phenotypes) may be effects of society rather than caused by biology

• Inappropriate behaviors (e.g., rape) may be justified on a biological basis

• Relative absence of quantitative data