Nature: This refers to all those characteristics and abilities that are determined by your genes. This is not the same as the characteristics you are born with, because these may have been determined by your pre-natal environment. In addition, some genetic characteristics only appear later in development as a result of the process of maturation. Supporters of the nature view have been called ‘natavists’.
Nurture: This refers to the influences of experience, i.e., what is learned through interacting with both the physical and social environment. Supports of the nurture view are ‘empiricists’ holding the view that all knowledge is gained through experience. You may be familiar with the term ‘empirical support’, where data is collected through sensory experiences rather than a reliance on thoughts and ideas.
It has been notes that neither nature or nurture can on their own provide complete explanations. All characteristics are a product of nature and nurture. Hebb used the analogy of the length and width of a rectangle – neither can be said to contribute more to the area of the rectangle, they are both important.
Research into Nature:
Strengths and Weaknesses
Assumptions made in research about the nature approach:
Evolutionary explanations of human behaviour exemplify the nature approach is psychology. The main assumption underlying this approach is that any particular behaviour has evolved because of its survival value.
E.g., Bowlby suggested that attachment behaviours are displayed because they ensure that survival of an infant and the perpetuation of the parents’ genes. This survival value is further increased because attachment has implications for later relationship formation which will ultimately promote successful reproduction. Evolutionary psychologists assume that behaviour is a product of natural selection in the environment of evolutionary adaptation (EEA). Interpersonal attraction can, for example, be explained as a consequence of sexual selection. Men and women select partners who enhance their productive success, judging this in terms of traits that ‘advertise’ reproductive fitness, such as signs as healthiness (white teeth) or resources. Physiological psychology is also based on the assumption that behaviour can be explained in terms of genetically programmed systems. Genetic theory of gender identity/role
This theory suggests that gender identity/role is not learnt, but inherited through genes from our parents. Evidence has been provided by the Reimer twin study. Both babies were born genetically male, with an XY sex chromosome, however after a surgical accident one of the boys was then raised as a girl. Although all efforts were made by Money, a leading gender psychologist at the time, the experiment failed and the boy rejected his socialised female identity. This clearly shows that genetic factors play an important role in gender identity/role development.
Bowlby’s explanation of attachment does not ignore environmental influences, as is generally true for evolutionary explanations. In the case of attachment theory, Bowlby proposed that infants become most strongly attached to the caregiver who responds most sensitively to the infants needs. The experience of sensitive caregiving leads a child to develop expectations that others will be equally sensitive, so that they tend to form adult relationships that are enduring and trusting.
Problem of the transgenerational effect.Behaviour which appears to be determined by nature (and therefore is used to support this nativist view) may in fact be determined by nurture! e.g. if a woman has poor diet during her pregnancy, her unborn child will suffer. This means that the eggs with which each female child is born will also have these negative effects. This can then affect the development of her children a whole generation later. This means that a child’s development may in fact be determined by their grandmother’s environment (transgenerational effect). This suggests that what may appear to be inherited and in born is in fact caused by the environment and nurture.
Research into Nurture:
Strengths and Weaknesses
Assumptions made in research about the nurture approach:
The behaviourist approach is the clearest examples of the nurture position in psychology, which assumes that all behaviour is learned through the environment. The best known example is the, social learning explanation of aggression, using the Bobo doll. SLT proposes that much of what we learn is through observation and vicarious reinforcement. E.g., Bandura demonstrated this in his Bobo doll experiments. He found that children who watched an adult role model being rewarded for aggression towards an inflatable doll, tended to imitate that behaviour when later on their own with a Bobo doll. This supports the idea that personality is determined by nurture rather than nature. This provides us with model of how to behave. However, such behaviour becomes part of an individual’s behavioural repertoire through direct reinforcement – when a behaviour is imitated, it receives direct reinforcement (or not).
Another assumption of the nurture approach is that there is the double bind hypothesis which explains schizophrenia. They suggest that schizophrenia develops because children receive contradictory messages from their parents.
Behaviourist accounts are all in terms of learning, but even learning itself has a genetic basis. For example, research has found that mutant flies missing a crucial gene can not be conditioned (Quinn et al., 1979).
Furthermore, it can be argues that Skinner’s concept of reinforcement depends on an instinctive propensity to be reinforced by the pleasure resulting from having a drive met.
Research into Nature & Nurture
Strengths and Weaknesses
The extreme natavist view holds that we are born with certain perceptual abilities which develop through a genetically programmed process of maturation and which owe nothing to learning. Empiricists on the other hand, believe that we are born with only the most basic sensory capacity and that our perceptual abilities develop through experience and interaction with our environment. It is unlikely that our acquisition of perceptual skills can be fully explained by either one of these extreme views. It seems more likely that perceptual skills develop as a result of an interaction between innate and environmental factors. The two main theories of perception – Gibson’s direct theory and Gregory’s Constructivist theory. Gibson argued that perception is entirely innate because the sensory array is sufficiently rich in information for perception to take place without any additional cognitive input. Gregory pointed to the ambiguous and fragmentary nature of most sensory input, which must thus rely in expectations (derived from experience) to complete the perceptual process.
Blakemore and Cooper (1970) placed kittens in a cylinder where they could only see either vertical or horizontal lines from the time when they could first open their eyes. The kittens wore a cuff around their neck so they were not exposed to lines of any other orientation. After 5 months, they were allowed to see the real world, although they were blind to objects whose orientation was perpendicular to the ones they were exposed to. This can be explained because there are several types of cell in the visual cortex which appear to respond to lines and edges of particular orientations. When the kittens’ visual cortex was examined, it was found that the cells that usually respond to horizontal were absent in the vertically-lined rear kittens. Therefore, the biological system (visual cortex) has been altered through experience.
Until the middle of the 20th century, intelligence was widely regarded as mainly biologically determined. The amount of intelligence possessed by an individual was present at birth and would remain the same throughout life, regardless of experience of training (nature).
One study (Plomin) looked at the DNA of 50 US children with IQs of 160+, and compared it with the DNA of children with average IQs. It was found that the gene IGF2R on chromosome 6 was twice as common in the children with high IQs than in the others. This suggests that genes are a major influence on IQ. However, in the 1950’s there was a shift from the nature to the nurture side of the argument. Supporters of this view put forward arguments that intelligence was not genetically determined, but was due to the nature of an individual’s experience. It was argued that intelligence was malleable in early childhood. This lead to programmes in the USA called Head Start.
Piaget’s theory of cognitive development is of interest in connection with the nature-nurture debate. In essence, he accepted that nature and nurture are both important. Piaget assumed that nature played a significant point in understanding why all children pass through the same stages of cognitive development in the same sequence. According to his theory, innate, maturational changes within the brain account for the sequences of stages. Piaget claimed that children in every culture show the same general pattern of cognitive development, and he attributed that to innate factors. The speed with which children proceed through the various stages depends on environmental factors. In the environment (e.g., school) facilitates learning, the children’s cognitive development will benefit. Second, if there is a mismatch between a current experience and the child’s stored knowledge in the forrn of schemas, this creates a state of disequilibrium or lack of balance. This is an uncomfortable state that motivates the child to acquire new knowledge in order to return to a state of equilibrium. Third, the notion of maturation providing the impetus for children to proceed from one stage of cognitive development to the next implies that most children are definitely in a given stage. Piaget accepted to some extent that children’s specific learning experiences might influence how well they performed certain tasks. E.g., the children of Mexican potters seemed to be at a more advanced stage of cognitive development when tasks involved a ball of clay rather than beakers (Price-Williams et al., 1969).
Gibson’s theory cannot explain perceptual set because our tendency to distort ambiguous images relies on expectations (top-down processing). Gregory’s view has been criticised because it is based on studies of visual illusions, which are ambiguous and unrepresentative of all sensory data. There are several ways to resolve this apparent debate. One is to consider research on visual pathways suggests that visual data takes two routes through the brain after leaving the eye. One is the dorsal system, which is related to bottom-up, data driven processing; the other is the ventral system, related to top-down, experience driven perception. A second way to resolve this relies on research into visual deprivation by Blakemore and Cooper (1970) who found that kittens deprived of horizontal or vertical visual experience for five months could no longer see lines of that particular orientation – nurture (experience) had affected nature (the brain).
Blakemore and Cooper’s work illustrates ‘neural plasticity’ – the ability of the nervous system to adapt to the environment. Such plasticity, combined with neural spcialisation makes evolutionary sense. It is advantages for an animal’s brain at birth to have certain hard-wired capacities, such as the ability to respond to lines of certain orientations. At the same time, it is advantageous for the brain to adapt to environmental conditions and ‘specialise’ in the directions required by the environment so that the nervous system can be used efficiently.
The conclusion is that it is not possible to make a simple statement about the influence of genetic or environmental factors, because each assumes a different importance in difference conditions. Turkheimer (2003) found that in poor children the contribution of genetic factors to their IQ was very low (heritability of 0.10), whereas the contribution of genetic factors to the IQs of wealthy children was very high (0.72).
A weakness of the genetic argument and research is that it is reductionist. This is because by emphasising the importance of genetic factors in IQ, it tends to neglect the influence of cultural factors such as housing and poverty. If IQ was completely genetic, the correlation for MZ twins would always be 1, which it is not. This suggests that the genetic argument is an oversimplification. One strength comes in supporting research of deprived children. One study (Perry Pre-school Project) studied 123 poor African American children. At aged 3-4, the pps were divided into two groups – half received a weekly half day session of enrichment and active learning, plus a home visit. The other half got nothing. At age 5 the mean IQ of the experimental group was 95, whereas the control group’s IQ was 83. This suggests that cultural and environmental factors are involved in IQ.
Manipulation of variables: There is no agreement about how we might define or measure the environment in which a person grows up. There are no standard units of environment by which we might compare one environment against another. At best, the efforts to manipulate environmental variables focus on gross dimensions; at worst, the efforts to define and manipulate the environment are laden with value judgements about good and bad environments that have minimal empirical support (Horowitz, 1993).
One weakness is Piaget’s theory is reductionist. This is because he saw the development of thinking as based on innate and maturation factors. This means he neglected the importance of the social and cultural context in which children grow up. For example, he ignored the impact of teachers, parents and peers on a child’s thinking. This suggests his view is oversimplified.
The RELATIONSHIP between Nature and Nurture
Strengths and Weaknesses
It has been claimed that the environment and heredity do not act independently of one another, but interact. The ways in which this interaction may occur is:
The Diathesis Stress Model:
This model states that both a genetic predisposition to a mental disorder and environmental stressors are necessary for a condition to affect an individual. What is inherited in some cases of mental disorders is a predisposition to be vulnerable to it, not the disorder itself. In order for the disorder to emerge, an individual has to have the genetic vulnerability to the disorder and a particular stressor that brings it about. In some cases this stressor needs only to be very mild such as a teenager leaving home for the first time. In other cases, the stressor needs to be quite extreme, such as a troubled family life, in order for the condition to occur. So even within the genetic vulnerability there is wide individual variation (which may account for the fact that even people from loving, well balanced families can develop schizophrenia).
Phenotype and Genotype:
When considering the nature-nurture issue it is important to distinguish between an individual’s genotype and their phenotype. The total genetic make up of an individual is known as the genotype. Genes contain the instruction of producing a physical body, which in turn have an effect on psychological characteristics. The phenotype is the observable physical and behavioural characteristics of an individual; in other words, the phenotype is what an individual actually becomes. This phenotype is the result of both genetic and environmental influences. For example, two children may be born with a similarly high predisposition to suffer anxiety. If one then experiences a very stressful environment, he/she may become a very anxious adult and perhaps be prone to anxiety disorders such as phobia or OCD. The other may, in contrast, have a supporting and benign upbringing that results in a well-adjusted adult capable of coping well with anxiety-provoking situations. Their genotype are similar, but their phenotypes are very different. Genotype cannot be measured, only the phenotype, therefore they have face validity but they lack FES.
The Form of Interaction:
In genetics and the environment interact, then it is useful to consider ways in which this interaction could occur. In recent years, behavioural geneticists have argued that our genes may actually influence the type of environment we experience. Plomin (1977) identified 3 different kinds of interaction between nature and nurture:
Passive: relationships between genes and environment may occur because parents transmit genes that promote a certain trait and also construct the rearing environment. E.g., if we assume that musical ability is genetic, then musically talented children may assume to have parents who are musically inclined and who both provide genes and the environment that promote musical ability.
Reactive: Relationships between genes and environment may occur because genetically distinct individuals may evoke different reactions in those around them. E.g., musically gifted children may be chosen for special training and opportunities by teachers. An aggressive child may make others around him aggressive.
Active: Relationships between genes and environment may occur because individuals actively select experiences that fit in with their genetically influenced preferences. E.g., musically gifted children may seek out musical friends (reciprocal determinism).
Gottesman suggests that there is a reaction range, whereby the genes do not determine behaviour but they establish a range of possible responses that a person will show to different kinds of experiences. Therefore, the genotype sets the boundaries on the type of phenotype that will develop. With respect to intelligence, Shaffer (1966) provides an example of reaction range on 3 children. One has high gentic potential for intellectual development, one who has an average IQ and one whose intellectual development has limited growth. The first child has the widest raction range, varying from below average in a deprived environment to far above average in an enriched one. In contrast, the child with the least potential has a much more limited reaction range and shows a smaller variation across different environments. Therefore, the genotype sets the building blocks but the environment can build on this potential.
Nature via Nurture:
Ridley (2003) genes to not simply interact with the environment, they are activated by this experience. This switching is created by switchers on DNA. Our bodies have hundreds of these, which switch genes on and off. Thus, genes are the recipe for life and the environment influences how the genes will be expressed.
Using twin and adoption studies. Although it is effective to use twin and adoption studies there are many issues to consider. For example, although there are generally higher concordance rates for MZ than DZ twins it is never 100%, therefore other factors MUST be considered namely the environment and experience, also it may be that MZ twins are treated more similarly than DZ twins.
There are also issues of twins being reared apart. Faber (1981) reported that twins supposedly reported apart were ften raised by relatives in the same town, saw a lot of each other and sometimes went to the same school. Therefore, the environment was no where near as different as originally suggested.
You can also use the research from above from Nature or Nurture
Discuss the nature-nurture debate with reference to two or more psychological theories and/or studies (30 marks) 2a) Explain what is meant by the terms ‘nature’ and ‘nurture’ (5 marks) 2b) With reference to two or more psychological theories, discuss assumptions made about nature and nurture (25 marks) 3. “We are essentially a product of our genetic heritage, yet the environment plays an important role in determining how this heritage is manifested.” With reference to the issues in the quotation above, discuss the nature-nurture debate in psychology (30 marks) 4. Discuss different views regarding the relationship between nature and nurture (30 marks)