Biological Basis of Personality II'

1
Biological Basis of Personality II.

• Evolutionary Psychology and Animal
  Studies of Personality

2
Key Themes

• Evolutionary theory
• Adaptation
• Evolutionary theory, sexual strategies and
  altruism
• The evolution of individual differences
• Life history and personality
• Animal personality and the five factor model of
  personality.

3
Learning Outcomes

• Outline some key ideas and examples in
  evolutionary theory
• Outline the main elements and research of
  evolutionary personality and individual
  difference psychology
• Describe how the five factor model of personality
  has been used in animal personality research
• Present considerations of evolutionary
  personality and animal personality theory and
  research.

4
Adaptation

• Adaptation is a major part of the evolutionary
  natural selection process. If we take the human
  body we can see that many aspects of human
  biological functioning are adaptations. For
  example, muscles are adaptation allowing us to
  move and lift things. Eyes are an adaptation,
  allowing humans to see.
• In fact, it is possible to see a lot of body
  processes and to some degree behaviours
  (including personality) as adaptation. Indeed,
  there are three types of adaptation that allow us
  to understand the adaptations that a species
  might make domain-specific, functionality, and
  numerous.

5
Evolutionary Psychologyand Adaptation

• Domain-specificity All adaptive processes, be
  they biological or behavioural, are designed to
  solve a particular problem. Many biological
  processes, and some behaviours, are seen to solve
  a particular problem. For example, in biology the
  existence of opposable thumbs is of great
  interest. One of the characteristics most often
  identified as playing a role in human evolution
  is the opposable thumb. The evolution of
  opposable thumbs has allowed humans to do all
  sorts of tasks that aided their development and
  get round problems.

6
Evolutionary Psychologyand Adaptation

• Functionality All adaptations need to be
  functional. That is, they serve a purpose. Let us
  return to the example of opposable thumbs. Try
  the following activates without using your
  thumbs, tying shoelaces, or turning on a tap. As
  you can see doing these things are a lot harder
  to do. You can see that the development of
  opposable thumbs is more than just an anatomical
  fact. Evolutionary psychologists like to look at
  behaviour and also see what the function of it
  is.

7
Evolutionary Psychology and Adaptation

• Numerous Evolutionary psychologists also note
  that species develop numerous adaptive
  mechanisms. For example, the body has a number of
  biological mechanisms that allow humans to eat
  food, to consume, digest and get rid of wasteful
  food. Evolutionary psychologists take the same
  approach to behaviour.
• For example, when choosing a life-long term
  partner, one who is likely to rear children,
  there are a number of psychological mechanisms
  that you use to select that partner, assessment
  of looks, ability to provide, ability to support,
  approach to life, approach to children.

8
Individual Differences, a classic example

• while men can potentially create huge numbers of
  children during their life-span, women can only
  have one child at a time.
• as a consequence of this distinction,
  evolutionary psychologists have argued that there
  are differences between males and female mating
  strategies.

9
Nine Main Hypotheses and Evidence That Underlie
Men and Women Sexual Strategies (Buss Schmitt,
1993)
Table 9.2 Nine main hypotheses and evidence that
underlie mens and womens sexual
strategies Source Buss and Schmitt (1993)
10
Nine Main Hypotheses and Evidence That Underlie
Men and Women Sexual Strategies (Buss Schmitt,
1993) (Continued)
Table 9.2 Nine main hypotheses and evidence that
underlie mens and womens sexual strategies
(Continued) Source Buss and Schmitt (1993)
11
Evolutionary Personality and Personality and
Individual Differences Psychology.

• Evolutionary personality psychology explains the
  five factor model of personality.
• How individual differences arise The example of
  through co-operation and leadership.
• How an evolutionary concept called life history
  is related to personality.

12
The Constituent Facets ofthe Big Five Factors
Table 7.3 The constituent facets of the Big Five
factors Source Costa and McCrae (1985)
13
Buss theory of personality and adaptation.

• Evolutionary theory provides a framework for the
  central concepts of personality by
• Providing an understanding of the major goals of
  humans and the problems that need to be addressed
  so as to enable reproductive success
• The psychological mechanisms that have evolved to
  enable humans to reach these goals and solve
  these problems
• Personality and individual differences in
  behaviours that humans employ to reach goals and
  solve the problems that are obstacles to
  attaining those goals.

14
Buss theory of personality and adaptation

• Buss suggests that goal directed tactics and
  strategies employed by individuals are the
  building units of personality. Buss acknowledges
  that there is a huge amount of variance in
  individuals goals and how much effort they spend
  in achieving them. However, Buss maintains that
  an evolutionary theory of personality can provide
  us with an understanding of what human goals are,
  the strategies that exist for reaching the goals,
  and what behaviours exist for overcoming
  obstructions to these goals.

15
Buss theory of personality and adaptation

• Buss states that all humans live in groups, and
  living in groups has a number of rewards and
  problems in terms of reaching a societys goals.
  For example, if we were to presume that
  societies main goals are survival and the
  reproduction of the species, living in a group
  provides individuals protection from predators,
  enhanced opportunities for collective hunting,
  the sharing of resources, more chances for
  meeting a mate.
• Therefore, these advantages, from living in a
  group, increase its members chances of reaching
  these goals (survival and the reproduction of the
  species).
• However, living in a group also presents problems
  that hinder the goals. For example, conflict
  between members of the group and the spread of
  disease among group members may hinder the
  survival and the reproduction of the species.

16
Buss theory of personality and adaptation

• David Buss has used this social situation as a
  basis to explain how humans have developed
  certain personality traits to attain goals (for
  example, survival and the reproduction of the
  species) and overcome obstacles to these goals
  (for example, conflict within the group and the
  spread of disease).

17
Buss theory of personality and adaptation

• According to Buss, personality traits such as
  being calm (low neuroticism), active, sociable,
  adventurous and person-orientated (extraversion),
  co-operative and trustful (agreeableness),
  practical, reliable, hardworking, ambitious and
  organised (conscientiousness) and sophisticated,
  knowledgeable, curious and analytical (openness)
  are all traits that would allow members of the
  species to co-operate to achieve goals (survival
  of the species) and overcoming problems (conflict
  between members of the group).

18
How individual differences arise through
co-operation Leadership.

• Rands, Cowlishaw, Pettifor, Rowcliffe
  Johnstone, 2003).
• The explanation they provide is based on a game
  called Prisoners Dilemma. Prisoners Dilemma got
  its name from a certain hypothetical situation

19
The Prisoners Dilemma
Figure 9.1 The Prisoners Dilemma
20
How individual differences arise through
co-operation Leadership.

• Specifically, they used the Prisoners Dilemma to
  explain how leadership and following behaviour
  might emerge among the same species.
• Rands and his colleagues use the example of two
  foraging animals.

21
How individual differences arise through
co-operation Leadership.

• All foraging animals seek balance between eating
  enough to avoid starvation and avoid being eaten
  by predators
• The assumption is that a rabbit will only forage
  when it is hungry, and foraging will increase
  their energy levels
• Then, after eating, over time their energy levels
  will fall until they are hungry again.
• when the rabbit has high energy levels it will
  not tend to forage because it is not worth the
  risk of being killed.
• A rabbit will only forage when they are hungry
  and their energy levels are low.

22
How individual differences arise through
co-operation Leadership

• However, Rand et al suggest that between two
  foraging animals they reduce the risk of being
  killed by a predator if they forage together.
• If both rabbits dont forage then their energy
  levels decrease but they dont get killed
• If one or the other of the rabbits forages alone,
  then they will individually increase their energy
  levels but run a greater risk of being eaten.
• if they both forage together they will increase
  their energy levels but decrease their chances of
  being eaten by a predator.
• Clearly then, the optimum strategy for the
  rabbits will be to forage together.
• Consequently, there is a tendency for the rabbits
  to only go out when one of the animals is
  starving, to reduce the risk of being killed.

23

• Rand and his colleagues postulated what would
  occur if two foraging animals met, where one had
  higher energy levels than the other (e.g. if one
  was fatter than the other).
• the rabbits would only go out when one of the
  rabbits was hungry, that is, the rabbits would
  forage whenever the thinner of the two got
  hungry.
• When this happened they would both replenish
  their energy levels. However, as the fatter
  rabbit would also be topping up the energy
  levels, the rabbit that was thinnest to start
  with would always get hungry first.
• The rabbits would only forage when the thinner
  rabbit got hungry. In this situation the thinnest
  rabbit would make decisions about when to forage.

24
Illustration of the Outcomes from Co-operation
and Non-co-operation Between the Two Rabbits in
Their Foraging Behaviour
Figure 9.2 Illustration of the outcomes from
co-operation and non-co-operation between the two
rabbits in their foraging behaviour
25
Life History and Personality

• Life history
• Mating effort
• Parental investment.

26
Life History and Personality.

• life history describes a schedule of growth,
  survival and reproduction throughout the
  individuals life that maximises reproduction and
  survival.
• They can do this in two ways. The first is
  through mating as much as possible (mating
  effort) and enhance their chances of greater
  reproduction (i.e. creating more offspring).
• The second is to spend more time with their
  existing offspring to ensure their survival, for
  example by feeding them or protecting them from
  predators. This is parental investment.

27
Life History and Personality.

• Kevin MacDonald suggests that the trade-off
  between mating effort and parental investment is
  a central dimension of reproductive strategies
  that range from
• a high parental investment/low mating effort
  strategy, to a
• low parental investment/high mating effort.
• Rushton (Rushton, 1985) used such an idea to
  develop his Differential K theory. Within this
  theory, Ruston suggests that life history might
  be useful to understand human individual
  differences by looking at individual and group
  differences in life histories, social behavior,
  and physiological functioning.
• He called the central dimensions that represent
  the trade-off between parental investment and
  mating effort as K.

28
Life History and Personality.

• U.S.A. psychologist Aurelio José Figueredo and
  his colleagues (Auerlio et al, 2005) examined
  Rushtons idea of K and MacDonalds idea that K
  might be related to personality.
• Childhood attachment to and parental investment
  from the biological father Emotional closeness a
  child felt toward either the biological father or
  surrogate father figure.
• Adult attachment to romantic partners. The
  security and emotional closeness a person
  generally experienced in their relationships
• Mating effort. The amount of energy or resources
  an individual invests to attract potential sexual
  partners and/or maintain relationships with
  current sexual partners.
• Machiavellianism This is a term used by
  personality psychologists to examine a person's
  tendency to deceive and manipulate others for
  personal gain.
• Risk-taking attitudes This is a term regarding
  people attitudes or abilities to take risks.

29
Visual Summary of Figueredo et als Findings
Between Life History (K factor) and Personality
Figure 9.3 Visual summary of Figueredo et al.s
findings between life history
( K-factor) and personality
30
Animals and Personality

• Gosling states variation within a species is
  important to personality psychologists because it
  hold clues to the nature of evolution of
  personality traits within a species and enables
  researchers to identify the adaptive nature of
  traits that allows it to develop, evolve and
  survive.
• Variations across species are important to
  consider because this can be used to examine the
  origins and adaptations of particular traits.

31
Reliability of rating among animals

• Across Raters There is evidence that observers
  agree in animal personality studies (Gosling,
  2001). For example, for inter-observer studies,
  three studies (Crawford, 1938 Hebb, 1949 King
  Figueredo, 1997) have found acceptable levels of
  inter-observer agreement in measuring dominance
  (observer correlation .70), friendliness
  (observer correlation.90)and dominance among
  chimpanzees (observer correlation .61).
• Over-time Crawford (1938) found a correlation
  statistic of .71 for confidence and .81 for
  cheerfulness for chimpanzees over a 4 week
  period. Stevenson-Hinde found that three
  personality traits, excitability, sociability and
  confidence in rhesus monkeys, were found to be
  consistent (above r .7) over four years of
  observation, even though different raters were
  used at different times.

32
Validity of animal personality ratings

• Capitanio (1999) tested the predictive validity
  of animal personality measures on 42 rhesus
  monkeys. Capitanio found that ratings of
  sociability were found to be negatively
  associated with antagonistic behaviour three
  years later.
• Gosling (1998) found that female hyenas scored
  higher on an assertiveness dimension than male
  hyenas. This finding is consistent because hyenas
  live in a matriarchal society (where females rule
  the family).
• Feaver et al. (1986) found that cats who had been
  rated aggressive previously spent more time in
  conflict situations (hitting or chasing) than
  other cats that had been previously rated as not
  aggressive.

33
Animals and Personality

• One important aspect of Goslings work has been
  the finding that core personality dimensions
  among animals are similar to those of core
  personality dimensions that have been found among
  humans.
• Openness (perceptive, sophisticated,
  knowledgeable, cultured, artistic, curious,
  analytical, liberal traits)
• Conscientiousness (practical, cautious, serious,
  reliable, organised, careful, dependable,
  hardworking, ambitious traits)
• Extraversion (sociable, talkative, active,
  spontaneous, adventurous, enthusiastic,
  person-oriented, assertive traits)
• Agreeableness (warm, trustful, courteous,
  agreeable, cooperative traits), and
• Neuroticism (emotional, anxiety, depressive,
  self-conscious worrying traits).

34
Animals and Personality

• Gosling and John (1999) looked at nineteen
  studies that have used a statistical technique
  called factor analysis to look for personality
  traits.
• Of the nineteen studies reviewed, seventeen of
  the studies found a behaviour that could be
  described as extraversion whether it be a lively
  temperament in a dog, sociability in a pig or
  boldness in octopus.
• In fifteen of the studies Gosling and John found
  behaviours that reflected a neuroticism factor.
  Examples of neurotic traits included fear in
  rhesus monkeys, nerve stability in dogs and
  emotionality in rats.
• In fourteen of the studies reviewed there was
  evidence of behaviours that reflected
  agreeableness including aggression and hostility
  (low agreeableness) in monkeys, affection in dogs
  and a tendency to fight (low agreeableness) in
  rats.
• In terms of the other two five-factor
  personality dimensions, openness and
  conscientiousness, Gosling and John found some
  evidence that these personality dimensions
  occurred in animals.
• In terms of openness, in 7 species studied,
  chimpanzees showed levels of openness and
  monkeys, hyenas and pigs all showed curiosity.
  Finally, in terms of conscientiousness.
• Gosling and John found evidence of
  conscientiousness personality traits, but only
  among chimpanzees.

35
An evolutionary interpretation

• Extraversion, neuroticism and agreeableness were
  found in the majority of studies, openness and
  conscientiousness were found in the large
  minority of studies, with conscientiousness only
  being found among chimpanzees.
• However, Gosling and John speculate how these
  differences between species might inform our
  understanding of how personality evolves.
  Conscientiousness comprises a number of advanced
  cognitive processes, such as following rules,
  establishing norms, creating and understanding
  values and acting, or refusing to act on impulse.
• Gosling and John speculated that as chimpanzees
  are humans closest relatives, and that one
  reason for this is that conscientiousness as a
  personality factor might reflect evolutionary
  development, and this finding might be of
  interest to psychologists in understanding the
  evolutionary development of personality.

36
A Model of How Personality might Evolve From an
Evolutionary Perspective
Figure 9.4 A model of how personality might
evolve from an evolutionary perspective
37
Problems with Evolutionary Theory

• Lewontin (1991) provides some reservations
  regarding evolutionary psychology, which apply to
  Buss evolutionary model of personality. First,
  Lewontin suggests that evolutionary theory
  provides little opportunity for empirical testing
  of the theory. Indeed, much of the theory for
  evolutionary theory involves speculations
  regarding behaviors across a number of
  generations.
• Second, Lewontin has suggested that evolutionary
  psychology is open to reductionism. Reductionism
  is a tendency to explain a complex set of facts
  or ideas by a simpler set of facts or ideas.

38
Key Themes

• Evolutionary theory
• Adaptation
• Evolutionary theory, sexual strategies and
  altruism
• The evolution of individual differences
• Life history and personality
• Animal personality and the five factor model of
  personality.