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Personality and Individual Differences > TASK 5 - GENETIC + ENVIRONMENTAL INFLUENCES > Flashcards

TASK 5 - GENETIC + ENVIRONMENTAL INFLUENCES Flashcards

1
Q

family studies (similarities between relatives)

A

= studies that correlated degree of genetic relatedness among family members, with degree of personality similarity
- highly heritable: family members with greater genetic relatedness should be more similar to each other (parents more than cousins)
x families usually share same environment –> difficult to disentangle the influence of genes and environment

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2
Q

results of family studies

A
  • different correlations have been found
  • biological relatives tend to be similar in personality (identical twins being much more similar than other kinds of relatives)
  • similarity does not depend on whether or not they have been raised together
  • substantial role of heredity in personality variation, but little (if any) role of common/shared environment
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3
Q

adoption studies

A
  • genetically related individuals who don’t share a common environment –> similarity estimates contribution of genetics to family resemblance
  • family members who share an environment but aren’t genetically related –> similarity estimates contribution of a shared environment to family resemblance
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4
Q

adoption studies

- other relatives raised apart

A
  • 50% of genes in common
  • similarity between them, we see effect of only 50% of the genes
  • doubling the similarity
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5
Q

twin studies

A

= compares identical twins (MZ) with fraternal twins (DZ)
- genetic cause for trait: identical twins more similar than fraternal ones
- twins raised apart (adoption studies)
- twins raised together (vs. fraternal twins)
x assumption of representativeness: twins are usually not really representative for whole population –> findings cannot be generalised
x twins often born 3-4 weeks prematurely (language develops slower)

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6
Q

results of twin/adoption studies

- twins raised apart

A
  • 100% of genes in common = genetic influence
  • similarities can be assumed to be due to genetics –> if separated right after birth
  • .60: twins more similar to each other than to unrelated people in that trait –> 60% of variance among people can be explained by heredity
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7
Q

results of twin studies

- twins raised together

A
  • 50% of variation due to genetic influences (self- / observer-reports)
  • 65% of variation due to heritability (self- + observer-reports)
  • -> almost all of that genetic variation was additive, almost none was non-additive
  • remaining variation: due to unique environment influences, due to common environment influences
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8
Q

additive vs. non-additive

A

additive effects = each gene separately contributes to personality (make level of trait a bit higher or lower)

non-additive effects = combined effects of genes are more complex (e.g. effect of one allele depends on presence of another)

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9
Q

shared environmental influences

A

= effects of environment shared by any twins who have been raised together; between-family (differ between families)
- same socio-economic status, religious attitude, parenting style

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10
Q

unique/non-shared environmental influences

A

= effects that differ even for individuals from the same household; within-family (differ within families)
- different friends, treated different by parents

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11
Q

assumption of heritability study

- personality is measured independently

A

WRONG: similarities between relatives are inflated/deflated; compare themselves/relatives not to general but to each other
1. contrast effect = emphasise difference between related persons
- larger effects in fraternal twins
2. assimilation effect = emphasise similarities between related persons
–> effects could influence people’s personalities: might really become more different/similar
overcome effects:
- reports from someone who knows one individual well, but not the other (cannot contrast/assimilate)
- direct observations: only observes one relative

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12
Q

assumption of heritability study

- there is little assertive mating

A

‘TRUE’ for some characteristics: parents are not similar in some personality characteristic (BUT in beliefs, attitudes)

  • similarity would not cause any important distortion
  • assortative mating would cause parents to sharing genes –> inherit genetic tendencies –> more similar (=overestimate heritability)
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13
Q

assumption of twin-based heritability studies

- twins’ early environment is separate

A

TRUE: similarity between twins raised apart is not attributable to early time spent together

  • similarities in womb environment: shared + non-shared environment
  • common environment: consistent across pregnancies (smokes during all pregnancies)
  • unique environment: features that change across pregnancies (eating a lot of meat in first pregnancy, being vegetarian in second)
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14
Q

assumption of twin-based heritability studies

- adoptive households are different

A

WRONG: reduced variability in adoption families (higher socioeconomic status, less antisocial behaviour); very little selective placement
- selective placement: families may be selected due to similarity to biological parents
x unlikely have important effects

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15
Q

assumption of twin-based heritability studies

- identical/fraternal twins receive same treatment

A

TRUE: similarity of identical twins is not due to similar treatment of those twin
- equal environments assumption = greater similarity of identical twins is due to greater genetic similarity, not due to greater similarity of environments

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16
Q

Reasons why/how variation persists

A
  • selection would tend to eliminate all variation (single, ‘best’ solution)
    WRONG: not a single ideal level of each trait
    1. variation is unimportant: has no consequences for survival and reproduction
    2. mutations cannot be eliminated quickly enough and reproduce in following generation
    3. importance of variation against infections by parasites: variations make it more difficult for parasites to invade bodies successfully
17
Q

balancing selection

- fluctuating optimum

A

= ideal levels of a characteristic vary across places and times = ideal level of same characteristic shifts according to changes in environment

  • average level of trait gradually shifting up/down within given population –> amount of variation not reduced
  • e.g. food abundant/shortage: many offspring = better reproductive success with abundant, few offspring = better with shortage (better parental care)
18
Q

blinking selection

- frequency dependence

A

= the advantages of doing what others are not doing = nearly everyone had high level of characteristic, few people who had low level of characteristic would be more successful

  • rough balance in population between people with higher and lower levels BECAUSE only advantage when they are few with low level
    e. g. females are attracted to rare colours: many green males + lone blue male = better reproductive success of blue males –> more blue males in next generation = advantage of blue decreases –> green males become more favoured
19
Q

how do fluctuating optimum + frequency dependence preserve variation

A
  1. favour reproductive success of individuals who have genetic inclination to have particular level of the trait
    a. either high or level of trait –> over long run produce equal levels of reproductive success of different levels
  2. favour reproductive success of individuals whose genetic inclination is more flexible –> allowing the development of high or low level of trait
    a. individuals adapt successfully; develop different levels of trait in response to cues of environment
20
Q

life-history theory

A

= trade-offs in problems of life to which limited energy is allocated

  • optimal trade-off depends on variables like own qualities, life expectancy & energy
  • individual differences
21
Q

costly signalling theory

A
  • individuals compete with one another in sending signals to others about their quality
  • deception
  • costly signals tend to be honest as not everyone can afford it
  • link to life-history (e.g. male can’t afford signal as short-term mate so might shift to life-history strategy of heavy investment in one long-term partnership)
22
Q

balancing selection

A

= occurs when genetic variation is maintained by selection

- different levels on trait dimension are favoured/adaptive in different environmental conditions to same degree

23
Q

mutation load

A

= we differ in mutation load

- heritability of some traits comes from differences in mutation load

24
Q

contingent shifts

A

= situation-specific shifts = select species-typical psychological mechanisms that are flexibly responsive to changes in environmental conditions

  • reactive heritability = contingent shift in response to one’s heritable phenotypic characteristics
  • life history theory: become more risk averse after becoming a father
  • costly signalling theory: when an environmentally contingent increase in mate value affords a greater ability to emit costly signals
25
Q

copy number variants + segmental duplication

A
  • segmental duplications = CNVs that have gone to fixation because selection favoured duplication
  • selection may favour changes in that segment so its function becomes different than that of the original copy
  • copy-paste-modify
  • much of human evolution occurred through changes in SD-rich regions
26
Q

difficulties in separating effects of heritability + environment

A
  • genotype-environment interactions = same environment influences peoples characteristics in different ways, depending on their genotype
  • makes relatives less similar to each other
  • genotype-environment correlation = genetic tendencies cause you to be more exposed to a specific kind of environment
    1) passive: inherit combination of genes + environment passively, not as result of own behaviour
    2) reactive/evocative: other peoples’ reactions to kid’s genetic tendencies end up influencing the environment
    3) active: child actively chooses environment as a function of genetic predisposition
27
Q

what accounts for genetic variability in general? (GANGESTAD)

A
  1. no selection: no meaningful selection on a trait; very unlikely
  2. mutation-selection balance: without mutations, selection would eventually eliminate variability around intermediate optimum; mutations do not die out
  3. variable selection: selection itself may be variable (spatially or temporally)
  4. negative-frequency dependent selection: when variants are rare in population they tend to success
  5. non-additivity: genetic variance non-additive is typically not removed by selection
28
Q

adaptive trade-offs

- Honesty-Humility

A

interpretation:
- reciprocal altruism (fairness, sincerity, modesty)
benefits of high levels:
- gains from cooperation (mutual help, non-aggression (= altruism))
costs of high levels
- loss of potential gains that would result from exploitation of others

29
Q

adaptive trade-offs

- Agreeableness

A

interpretation:
- reciprocal altruism (tolerance, forgiveness)
benefits of high levels:
- gains from cooperation (mutual help, non-aggression)
costs of high levels:
- losses due to being exploited by others (as they keep cooperating in spite of some unfairness)

30
Q

adaptive trade-offs

- Emotionality

A

interpretation:
- kin altruism
benefits of high levels:
- survival of kin personal survival by avoiding harm
costs of high levels:
- could enjoy greater gains as a result of confronting dangers

31
Q

adaptive trade-offs

- Extraversion

A 
interpretation:
- engagement in social endeavours
benefits of high levels:
- social gains (friends, mates, allies)
costs of high levels:
- energy + time + risks from social environment
32
Q

adaptive trade-offs

- Conscientiousness

A 
interpretation:
- engagement in task-related endeavours
benefits of high levels:
- material gains (improved use of resources), reduced risks
costs of high levels:
- energy + time
33
Q

adaptive trade-offs

- Openness to experience

A 
interpretation:
- engagement in idea-related endeavours
benefits of high levels:
- material + social gains
costs of high levels:
- energy + time + risks from natural environment

Personality and Individual Differences (8 decks)

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