WJEC A2 Psychology PY4 - Controversies: Genetic and Environmental Influences on Behaviour

Genetic Influences

• are referred to as 'nature' influences which are inherited from parents in the short term, and our evolutionary ancestors over the long term
• genetic influences do not simply refer to abilities present at birth, but to any ability determined by genes, even those which lie dormant for a number of years and appear later through maturation
• example: genetic development of the visual perceptual system, which together with exploration of environments as we become mobile, influences depth perception

Environmental Influences

• are referred to as 'nurture' influences, which are learned (acquired) through interactions with environment and includes both physical and social world, and may be more widely referred to as 'experience'
• concept was originally put forward by empiricist philosophers who believed we were all born 'Tabula Rasa' (blank slate to etch experiences onto)
• example: social influences of role models who have seen to be rewarded for their aggressive behaviour towards a Bobo Doll in Bandura's expts in 1960s

1. Genetic Basis for Intelligence - undoubtedly genes play role in affecting behaviour

POINT = gene mapping studies have attempted to identify individual genes which are responsible for intelligence as it is believed they influence levels of intelligence

EXAMPLE/EXPLANATION = Chorney et al (1998) found certain individual genes associated with IQ, eg in 46% of 51 super-bright children, identified gene IGF2R (insulin-like growth factor 2) on chromosome 6, same gene present in 23% of 51 average IQ children. Study highlights that genes are hugely important in intelligence levels and that by possessing a certain gene, this can cause very high levels of intelligence ("genius" level)

COUNTER ARGUMENT =  (-) however critics have interpreted results of Chorney's study as not emphasising genetic differences in intelligence (and importance of possessing gene to have high intelligence) but illustrating the potential for environmental influences, as majority of super-bright children (54%) didn't actually possess gene (but still as intelligent as those who did) and some of average IQ children had gene yet not as intelligent - therefore perhaps genes don't have much influence on intelligence levels?

(?) Turkheimer et al (2003) interestingly showed genetic factors mattered depending on socioeconomic status of children. In children from affluent families, about 70% of variance in IQ scores accounted for by genes, but for children from impoverished fams, only 10% of variance. Shows for these genes to have impact on intelligence levels depends on environment (like socioeconomic status). With C's study, the 23% of average IQ children with IGFR2 gene may have had same level of intelligence as super-bright children with gene, but didn't due to their environmental surrounding

2. Genetic Basis for Schizophrenia

POINT = been suggested genes are responsible for mental illnesses. Twin studies shown that the closer two individuals are genetically, more likely both of them will develop same mental disorder, like Sz

EXAMPLE/EXPLANATION = eg Gottesman and Shields (1972) found concordance rates for Sz is about 50% for MZ twins (100% identical) and 10% for DZ twins (50% identical). Emphasises genetic influence because it shows Sz caused by genetics, as seen with 50% of MZ twins, who are 100% identical - therefore, genes must undoubtedly play role in causing Sz and has an influence on behaviour

COUNTER ARGUMENT = (-) however, study shows that environmental component must contribute to causing Sz otherwise the concordance rate for MZ twins (100% identical) should be 100% if solely genetic. Could be due to diathesis-stress model: individuals with genetic vulnerability (diathesis) only develop it under certain trigger conditions (stress) (eg high EE interacts with genetic vulnerability and triggers Sz) Could explain 50% CR of MZ twins: both twin have genetic vulnerability but 1/2 experience environmental factor, triggering disorder

3. Genetic Basis for Mate Selection

POINT = in support of genetic influences on behaviour argument, sexual selection has been shown to have major genetic influence

EXAMPLE/EXPLANATION = Buss' evolutionary study (1989) showed characteristics we look for in a mate are universal (in our genetic makeup to look for these) eg women seeking partner who provides financial security. Shows that behaviours which promotes survival + reproduction will be naturally selected as it's adaptive and thus genes for that behaviour will be passed on to subsequent generations. Buss shows such behaviours are global = implies there must be genetic basis

COUNTER ARGUMENT = (-) however such genetic behaviours are modified by culture. Different cultures look for different things in mate selection. In Spain and Colombia, men all rated ambition as more important in women than women did in men. In Zulu culture, women do all physical tasks such as building the house, which Zulu men rated as important when choosing a mate. Many characteristics seem universal and has genetic influence but clear that culture also has effect on mate selection

1. Environmental Basis for Phobias

POINT = suggested that phobias are caused by environmental influences

EXAMPLE/EXPLANATION = Watson and Raynor's (1920) study of 'Little Albert' showed power of environmental influence on developing phobias, after classically conditioning an infant to be scared of an animal he had previously shown no fear of (rats). Study shows that associations built up between neutral stimuli and (accidental or intentional) environmental events can determine our behaviour

COUNTER ARGUMENT = (-) however even Watson acknowledges existence of at least 3 inherited characteristics: rage, fear, love, called basic pattern reactions. Watson also accepted certain reflexes were inherited, as these were the unconditioned responses which formed basis of classical conditioning. Even if Watson believed we were all born 'Tabula Rasa', he did acknowledge that we inherited the blank slate so that environmental experiences could be etched onto it and this inheritance highlights the influence of genetics

2. Environmental Basis for Aggression

POINT = environmental influences on behaviour have shown that they can contribute to aggression

EXAMPLE/EXPLANATION = Bandura's view was that aggressive (possibly criminal) behaviour is mainly learned through environmental factors such as observation and vicarious reinforcement, which are key concepts of social learning theory (SLT). Bandura et al (1961)'s classic study using the Bobo Doll illustrates the environmental influence on aggression, where kids who witnessed an aggressive role model rewarded for their behaviour were more likely to copy them than those who didn't see the model rewarded

COUNTER ARGUMENT = (-) however biological potential for aggression is not equally distributed in a population - not all of the children copied the rewarded role models equally, therefore it doesn't rule out the possibility of biological (genetic) predispositions to act aggressively or criminally, therefore genetic influences may impact on causes of aggressive behaviour

CONCLUSION

• balance of genetic and environmental influences on behaviour is false dichotomy, it is combination of both and this agrees with concept of interactionism and could be explained by epigenetics for example
• idea that as a person experiences environmental changes (eg famine), genes are altered (switched on or off) - this altered 'switched on/off' gene is then passed onto offspring (kind of genetic 'memory' for environmental conditions)
• suggests interaction between genes and environment which is ultimately important because to assume behaviour is one or the other is reductionist and oversimplifies human behaviour despite evidence that nature and nurture interact