Biology Essay - Critically evaluate how biological and environmental factors influence human PDF

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Critically evaluate how biological and environmental factors influence human behaviour...

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Biological Psychology P2523134 Critically evaluate how both biological and environmental factors influence human behaviour. Support your argument using empirical evidence.

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Introduction Different aspects of an individuals behaviour are influenced by their biology, environment and a combination of both. This essay will discuss how biological and environmental factors such as genetics, heritability, brain activity, culture, peer groups, life experiences, and parental support influence an individuals behaviour such as their personality. To support these arguments theorists such as Eysenck, Fleischman and Bouchard but not limited to will be used to further explain the influences on personality. Defining personality has been a controversial issue for several years, mainly because the concept of personality is so wide, which makes it difficult to conceptualise succinctly. One definition of personality can be described as the dynamic organisation within the individual of those psychophysical systems that determine his or her behaviour, thoughts, and feelings (Allport 1961). Biological psychologist such as (Burger, 2008) believed that physiological processes, as well as inherited predispositions, can be used to explain personality differences. Twin studies are an integral part of the nature-nurture debate, in terms of whether genetics have a stronger influence on personality compared to environmental factors or vice versa. The Minnesota study of twins reared apart conducted by (Bouchard 1994, Mcgue, Lykken, Tellegan and Segal 1990; Segal, 2012) supports the nature side of the debate. They studied 350 pairs of identical(monozygotic) and fraternal(dizygotic) twins raised together and apart between 1979 and 1999. The findings of the study showed that personalities of monozygotic twins, were similar whether raised together in the same environment or apart. The study reported the heritability of some personality traits. Although this study did not find similarities between monozygotic twins on measures such as standardised personality test, it can be used to show strong support for genetical influences on personality to a certain extent mainly because it is based on assumptions from the 20s which are immensely flawed. However it is argued that if the environment influenced individuals personalities, Dizygotic twins raised together would have had more similarities in personality than those raised apart but this is not the case (Plomin & Colledge, 2001). In terms of heritability, a recent study by Bouchard, Jr. (2004) offered a brief analysis of the heritability of psychological traits. Focusing on the big five personality traits, he found that they all show heritability ranging from 42 to 57. Thus it can be further argued that although genetics make a significant contribution to an individuals personality, the environment also contributes to the development of personality. P2523134

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Beside Bouchard et all,(Hans and Sybil Eysenck 1990 1992) also emphasised the biological nature of personality. He believed that personality traits are influenced by genetic inheritance and that environmental factors have little to no influence on personality. He opined that "personality is more or less stable and enduring organisations of a persons temperament, intellect, character and physique". Eysenck argued that individuals inherit a type of nervous system, which affects their ability to absorb and adapt to the environment. Eysenck worked at the Maudsley psychiatric hospital where his job was to assess every patient before they were diagnosed by a psychiatrist. Using factor analysis to collect data from the patients, he found that their behaviour could be explained by two dimensions as follows: Introversion/Extroversion and Neuroticism/Stability. He concluded that each of the dimensions can be traced back to a biological cause. For example, extroverts are impulsive, optimistic and carefree because they inherited an under -aroused nervous system and according to Eysenck seek stimulation to balance the level of optimum stimulation, whereas introverts are overly-aroused and therefore tend to avoid stimulation and sensation. In terms of neuroticism, Eysenck derived that an individuals level of neuroticism depends on the reactivity of their sympathetic nervous system, whereas a stable person's nervous system will be less receptive of stressful situations, remaining cool and level headed. On the other hand, someone high in neuroticism will be highly unstable and prone to overreacting and quick to anger, fear or worry. As mentioned previously, twin studies are very important in regards to studying whether genes influence personality, however, the findings of the study vary and are non-conclusive. In addition, the study conducted by Loehlin, Willerman and Horn (1988) found that 50% of the scores on personality dimensions were due to inherited traits suggesting that environmental factors are also important. Another biological factor that has been said to influence personality is the brain. A classic case study on Phineas Gage and illustrated the link between the brain and personality. Phineas was working on the railways in 1848 in America using a tamping iron which was used to compress explosions. The gunpowder went off prematurely and blew the iron in his left eye and later it was discovered that the iron pierced his frontal lobe. After the accident, Gage's once even-tempered personality changed dramatically, and he became emotionally inhibited. The findings from this case study informs us about what we now know about the frontal lobe, that damages to the frontal lobe can cause personality changes, aggression e.t.c.

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As mentioned previously, Loehlin, Willerman and Horn (1988) found that only 50% of the scores of personality dimension were due to inherited factors suggesting that the remaining 50% was primarily due to environmental factors such as culture family environment and parental attitude. The term culture is defined as traditions, beliefs, ideas, customs and behaviours passed through generations of a particular society. Each culture has its norms and values which dictates what behaviours are desirable or undesirable within that culture. For example, what is considered desirable in one culture may be undesirable in another culture and vice versa. Cultures are usually divided into two categories; individualist and collectivists. Based on these two categories the type of culture in which an individual lives in is one of the most important factors that shapes their personality (Triandis and Suh, 2002). Individuals that live or grew up in a collectivist culture tend to put the groups' needs over their own, value respectfulness and social harmony. These individuals tend to have more socially oriented personality traits such as agreeableness and conscientiousness, whereas individuals who live or grew up in individualist cultures, prioritise self-improvement of themselves and satisfying their own needs before the rest of those in their community and tend to have more personally oriented personality traits. Environmental psychologists believe that the environment accounts for approximately 50 per cent of an individuals personality. Factors such as peer groups, social media, family environment and parental attitude play a significant role in shaping individuals personalities. During adolescence, an individuals peer group is the most influential factor on their personality. This is primarily because at that age, they have similar similar interest, ideas, dislikes and likes, therefore they often behave like each other to be included in the group. Therefore the closer a peer group is, the more influential it is to its members. Harris (1995) argues that the reason peer groups are so influential in the development of their peers' personalities, is that during that age adolescents consider feedback received from their peer groups more important than that of parents and therefore alter their behaviours to fit the view of the group. Budhall (1998) identified a connection between isolation amongst peer groups and low self-esteem in adolescents supporting the argument that peers are important in the development of personality. However, it could be argued that peers don't necessarily influence individuals personality as people behave a certain way that's different from their personality in order to fit in with a group. Furthermore, it is argued that during adolescence an individuals personality, is also influenced by their parents despite them detaching themselves from their

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parents and spending time with their peers more. Parents provide emotional support and security which is immensely important in helping adolescents assert their independence during the early adolescence. Research by Brendgen, Warner, Morin and Vitaro (2005) found that "problematic relationships with parents increase the possibility of a depressed mood during early adolescence which in turn will result in these individual adapting a reserved personality. However, due to the limited research in how peer groups and parents influence personality, it's impossible to determine which factor has more of an influence. A persons life experiences is another environmental factor that influences their personality and establishes what type of person they will become or explain the kind of person they are. Life experiences according to Meyerin leave scars, but they may also leave an experiential residue, a memory capable of serving as something to be thought of, remembered and feared". For example, if a person that is described as having an "outgoing" or boisterous" personality experienced a stressful or traumatic life event, it is very likely they will experience significant changes in their personality possibly by becoming more introverted. A study was conducted by Bunce et al (1995) on 26 traumatised student and 30 non-traumatised students. In this study, they explored the differences in traumatised and non traumatised students personalities and daily life experiences. They found that traumatised individuals portrayed more trait anxieties and lower self-esteem compared to non traumatised students. The traumatised students were also more introverted and less emotionally stable than non traumatised individuals. The differences in personality between traumatised and non traumatised individuals suggest that the events people experience, whether good or bad influences the type of personality they have. However, it is argued that by Milkulincer and Florian, (1988)"insecure" individuals (those who display more negative emotions) are more likely to react and be influenced by negative life experiences that "secure" individuals (those who display more positive emotions), which might explain the differences between the traumatised and non traumatised individuals. In conclusion, an individuals personality is influenced by both biological and environmental factors such as genetics, culture, life experiences bain activity, heritability and peer groups. To say one influences personality in the absence of the other will most likely lead to error. However, through the use of twin studies, it can be seen that genetics are more influential than environmental factors as it showed that monozygotic twins raised together and apart had

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similar personalities. Brain structures also influence personality as seen through the case of Phineas Gage. The frontal lobe is whats responsible for individuals and their emotions so damage to the frontal lobe results in personality changes. Although personality is influenced mostly by our biology, the changes in personality are due to environmental factors such as life experiences. An individual who displays more positive emotions according to Mikulincer et al is less likely to be affected by negative life experiences but this does not mean they aren't affected at all and just like how personality changes due to life experiences, it is not permanent and with time an individual can regain their original personality. The culture in which an individual lives in is also an important factor that influences personality. Based on what norms and values a society or community have. It has an effect on the type of behaviour that is allowed so individuals are either brought up with those customs which influences their personality type or alter their personality to fit those of their community and conform. Similarly to culture, peer groups have the same effect on individuals in regards to people in the same group influencing each other's personalities through shared ideas and interest. However, it could be argued that peer groups have no effect on individuals as they act differently in their home environment compared to when they are with their peers so they might just be acting out a specific personality type in an effort to fit in. Parents also influence the development of individuals personalities by providing emotional support and security helping adolescents assert their independence, Which could result in them growing up to be emotionally stable and even-keeled.

References: Beckett, C., & Taylor, H. (2019). Human growth and development. SAGE Publications Limited. Bouchard, T.J. Jr, Lykken, D.T., McGue, M., Segal, N.L., Tellegen, A (1990). Sources of human psychological differences: the Minnesota Study of Twins Reared Apart. Science. 1990; 250(4978): 223–228. Bouchard Jr, T. J. (2004). Genetic influence on human psychological traits: A survey. Current directions in psychological science, 13(4), 148-151.

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Brendgen, M., Wanner, B., Morin, A. J., & Vitaro, F. (2005). Relations with parents and with peers, temperament, and trajectories of depressed mood during early adolescence. Journal of abnormal child psychology, 33(5), 579– 594. https://doi.org/10.1007/s10802-005-6739-2 Bunce, S. C., Larson, R. J., & Peterson, C. (1995). Life after trauma: Personality and daily life experiences of traumatized people. Journal of Personality, 63(2), 165-188. Eysenck, H. J., & Eysenck, M. W. (1987). Personality and individual differences. New York, NY: Plenum. Eysenck, H. J. (1963). Biological basis of personality. Nature, 199(4898), 1031-1034. Fleischman, J. (2002). Phineas Gage: A gruesome but true story about brain science. Houghton Mifflin Harcourt. Harris, J. R. (1995). Where is the child's environment? A group socialization theory of development. Psychological review, 102(3), 458. Loehlin, J. C., Willerman, L., & Horn, J. M. (1988). Human behaviour genetics. Annual review of psychology, 39(1), 101-133. Mikulincer, M., Florian, V., Simpson, J. A., & Rholes, W. S. (1998). Attachment theory and close relationships. JA Simpson. Revelle, W. (2014). Eysenck, Hans J.(1916–97). The Encyclopedia of Clinical Psychology, 1-3. Triandis, H. Suh, E., (2002). Cultural Influences on Personality. Annual review of psychology. 53. 133-60. 10.1146/annurev.psych.53.100901.135200.

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