Textbook Notes (363,084)
Canada (158,183)
Psychology (4,731)
Chapter 5

Chapter 5.docx

6 Pages
Unlock Document

Western University
Psychology 2550A/B
David Vollick

Part II: The Biological Level Chapter Five H EREDITY AND PERSONALITY Genetic Bases of Personality - Behaviour genetics: studies the role of genes in social behaviour and personality - Examining the genetic and biochemical roots of personality, including temperament, attitudes, beliefs, and behaviour - Consider social factors – family and culture The human genome: the genetic heritage - Human genome project – controversies sprout about the implications and the hazards of each new discovery - Arguments about understanding heritability of personality characteristics and behaviour tendencies Inside DNA: the Basic Information - Genetic heritage of each person is contained in a large molecule called DNA - 23 pairs of chromosomes - DNA is a long string of small units called nucleotides – only 4 types – A T G C - These small unites are strung together to form a long string - A trillion cells in the human body houses within its nucleus a complete and identical sequence of DNA o 1.5 gigabytes of genetic information Not really a blueprint - DNA is not a blueprint - Each and every cell in the body contains identical DNA – turn into nerve cells, specialized cells, or skin cells - Most of the DNA in these cells does nothing DNA-environment interactions - Reading the dna results in making the particular type of protein specified by the part of the dna that was read - What gets read in turn is determined by whats going on in the cell – which is influenced by what’s going on outside the cell, the molecules that are floating around, as well as nature of the neighbouring cells - Gene: region of dna that influences a particular characteristic in an organism, and is a unit of heredity - Genes contain a stretch of dna – specifies the structure of a protein to be made - Regulatory sequences: control whether or not, and how much of the protein is made - Sometimes different proteins can be made by the same gene – determined by the interaction between the cellular environment Individual differences in DNA - Unrelated people share 99.9% of their DNA sequence – DNA is not identical - Minor differences in a DNA sequence can lead to profound differences in the nature of the protein made based on the sequence - Variations among people in their DNA sequence could have important variations in how they look, feel, think, and behave Biological Switches - What a cell becomes is determined by biological switches outside the cell that turn the specific gene in the cell on or off - Although the genome provides options, environment determines the options that become activated - Past: focused on different types of people and the different genes they possess to determine what underlies the different personality types and characteristics - New: understand just how the genes are turned on and off by the physical and social-psychological environment and expressed, and the specific ways in which the process influences how we feel, think, and behave - Most studies compared the similarity in personality shown by individuals who vary in the degree to which they share the same genes and/or the same environment o Overall effects of these 2 determinants on individual differences on average - Genes play a role in personality and it is greater than what was previously suspected o Widely believed that dispositions as extraversion-introversion have biological-genetic basis Twin Studies The Twin method - Heredity studies use the twin methods to assess genetic influence - Method compares the degree of similarity on measures of personality obtained for genetically identical twins o Monozygotic (mz) or dizygotic (dz) Results of twin studies - Identical twin pairs are much more alike than fraternal twins pairs - Resemblance within identical twin pairs tend to be strongest for general ability o Lower for personality inventory scales and lowest for interest, goals, and self-concepts - For personality, twin correlations are about .5 for identical twins and .25 for fraternal twins - Nearly all personality traits measured by self-report questionnaire show moderate genetic influence The big five - Five broad dimensions of personality - Extraversion and neuroticism were studied the most - Extraversion: sociability, impulsiveness, and liveliness - Neuroticism: moodiness, anxiousness, and irritability - The role of heritability in extraversion and neuroticism has been studied extensively but much less genetic research has been done for the other 3 Big Five traits – Agreeableness (likeability, friendliness), Conscientiousness (conformity, will to achieve), culture (openness to experience) Temperaments - Temperaments refers to traits that are visible in early childhood, and seem especially relevant to the individual’s emotional life - Dispositions usually considered temperaments include the general level of emotionality, sociability, and activity - Assessed through parental reports for children are used - For adults – assessed through self-report measures - Emotionality (emotional reactivity): tendency to become aroused easily physiological and especially to experience frequent and intense negative emotions (anger, fear, distress) o Intensity that individuals experience emotions is independent of how often he or she has such feelings - Emotionality is an important aspect of temperament - Emotional reactivity at high levels may be a long-term risk factor for emotional disorders – and for some, somatic disease - Sociability: degree to which the person seeks to interact with other and to be with people - Activity: both to the vigor or intensity of responses and their tempo or speed – stable individual differences on a dimension that ranges from hyperactivity to extreme inactivity - Consistent results for genetic role in personality with regards to the temperaments of emotionality, activity, and sociability - Couldn’t use questionnaires to measures children’s temperament – so they directly observed the behaviour o Young twins show genetic influence for diverse characteristics  Fearfulness, shyness, activity levels, empathy - Inhibition (Kagan): one of the major dimensions of temperament – early individual differences exist on this dimension and endure in the course of development o Similar to neuroticism component of Big Five o These kids react to unfamiliarity with fear Attitudes And Beliefs - Genetic influences also seem to play a role in individual differences in attitudes are beliefs - Substantial genetic influence was found on traditionalism, a general orientation that taps conservative attitudes on diverse topics and many other attitudes also seem to show genetic influence - Attitudes that are more heritable may differ from those that are less heritable o Examining these differences helps with understanding of nature of genetic influences - More heritable traits were harder to influence and also more important in determining the person’s judgments of interpersonal attraction Aggressive And Altruistic Tendencies - Influence of genes on other aspects of social behaviour - With identical twins – answers are more similar than would be expected by chance whereas between fraternal twins.. Correlation was merely at chance level o Same for both males and females Romantic Love And Marriage - Genes directly or indirectly influence individual differences on most measures of personality – and social attitudes (self-esteem) - Romantic love is beyond dna - 6 different love styles were measured, ranging from one that values passion, excitement, intimacy, self- disclosure, and ‘being in love from the start’, to one that values a relationship that is affectionate and reliable and has companionship and friendship - How people love is almost completely due to the environment and essentially unaffected by genetic influences - Love styles may be learned during early familial or shared extra-familial interactions and played out in romantic relationships - Love styles seem not heritable – propensity to get married is Twins Reared Apart - Separate the role of genetics & environment – informative to assess identical twins who have been reared apart in different families - Most of the twins had not seen each other for an avg of about 30 years – some had contact over the years - Instances of dramatic psychological similarities o Share distinctive mannerisms, postures, attitudes, and interests o Some had same height, weight, number of children and marriages, drinking and smoking habits, clothing/food preferences, physical symptoms, scores on personality tests - Many felt close emotional connection with each other even though they had spent their entire lives apart - Similarity was almost as high for identical twins growing up in different homes as it was for those raised within the same family - Bouchard attributed approx. 70% of the individual differences found in intelligence to heredity Beyond Self-Report Measures - Many traits that have been studied, virtually all show genetic influence - Important to use measures of personality other than self-report questionnaires to investigate whether or not this result is somehow due to biases in the self-report measures themselves Understanding Heritability and the Heritability Index - Many misconceptions about the implications of heritability for personality - Heritability estimates always are limited to the specific po
More Less

Related notes for Psychology 2550A/B

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.