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


(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

(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