Chapters 6 & 7:The Biological Perspective

Theories of Personality

February 21, 2003Class #5

Sociobiology

• The theory that the basic elements of social interaction are products of evolution

• We are genetically predetermined to do certain things because at some point in prehistory they conferred an adaptive advantage to us

Helping requires investment of time, energy, attention, funds…so why do we do it?

• Goals of Prosocial Behavior– Gaining Genetic and Material Benefits

•Inclusive Fitness•Reciprocal Aid

Insights into the Evolution of Help

• Inclusive Fitness – The ability of one’s genes to survive in one’s

own offspring AND in any relatives one helps

– Helping a close relative promotes the survival of those genes

– We are predisposed to help the next generation (related to you) to reproduce

Genetic Relatedness and Helping

• Cunningham et al. (1995) – Asked people whether they would be

willing to help other people in different situations

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6060

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High(parents, siblings, children)

High(parents, siblings, children)

))

Percentage Volunteering to Help

Percentage Volunteering to Help

4040

Degree of RelatednessDegree of Relatedness

Mod. (grand-parents)

Mod. (grand-parents)

Low (first cousins)

Low (first cousins)

None (attractive strangers)

None (attractive strangers)

Reciprocal Aid• Trivers (1971)

– The theory of reciprocal altruism predicts that altruistic behaviors will also be a function of beliefs about the recipient's likelihood of reciprocating…

– Help that occurs in return for prior help

– People working for organizations who provide more benefits work harder for the firm

Who do you help?• Burnstein, Crandall, &

Kitayama (1994)– Participants in this study were asked to imagine

scenarios like the following:• There are three people asleep in different

rooms of a burning house:– Your 7 year-old female cousin– Your 75 year-old grandfather– A 21 year-old acquaintance

• You have time to rescue only one… – Who do you save?

3.03.0

2.52.5

1.51.5

1.01.0

High(parents, siblings, children)

High(parents, siblings, children)

, ,

Tendency to HelpTendency to Help 2.02.0

Degree of RelatednessDegree of Relatedness

Mod. (grand-parents)

Mod. (grand-parents)

Low (first cousins)

Low (first cousins)

None (acquaintances) None (acquaintances)

For everyday help, people tended to help close relatives more than non-relatives

For everyday help, people tended to help close relatives more than non-relatives

3.03.0

2.52.5

1.51.5

1.01.0

High(parents, siblings, children)

High(parents, siblings, children)

Tendency to HelpTendency to Help 2.02.0

Degree of RelatednessDegree of Relatedness

Mod. (grand-parents)

Mod. (grand-parents)

Low (first cousins)

Low (first cousins)

The difference became even more pronounced in life-or-death situations

The difference became even more pronounced in life-or-death situations

None (acquaintances) None (acquaintances)

Burnstein, Crandall, & Kitayama (1994)

• Kin are helped more than non-kin, especially in life-or-death situations

• Females are helped more than males, except elderly females (post- menopausal)

• Young are helped more than old • Healthy relatives helped more than non-

healthy in life-or-death situations • In life-or-death helping, relatedness matters

(this assures that our genes will continue)• In everyday helping, we may be guided more

by social norms and moral rules (e.g., "help the sick")

Genetic Similarity Theory

• Rushton (1984, 1989)– Proposes an extension to inclusive fitness

theory, in which the idea of "genetic similarity" between individuals is substituted for relatedness, as the more general and appropriate concept

– Idea that humans are able to detect degrees of genetic similarity in others and to prefer those most similar for friendship and marriage

– Unfortunately, this may be a process which provides a basis for ethnic favoritism and group selection

Mate Selection

• Trivers (1972)– The parent with the most investment

in an offspring will be the choosiest •Why?

– The parent with the most investment in most cases is the female because she has a limited capacity to reproduce because of a limited number of years to bear children

– Because of these limitations the female becomes highly selective in who she will mate with

Sex differences???• According to this view, this is the

reason why men view women as sex objects and women view men as success objects

Mate Retention

• Buss & Shackelford (1997) – Men married to younger women and to women

they perceived as being very attractive devoted great efforts to mate retention

– Women married to males with plentiful resources also showed more mate retention behaviors

– Men (but not women) whose partners they suspected may become unfaithful significantly increased certain retention behaviors

– Men were more likely to use resource-based tactics (and aggression) to retain a mate, while women were much more likely to use physical enhancement

The Young Male Syndrome• Wilson and Daly (1985)

– Present a Darwinian perspective on male violence

– The ultimate, evolutionary view provides an understanding of why males and females have come to have different reproductive strategies, involving greater competition and risk-taking between males than females, and conflicts of interests between males and females

– Most male violence - to other men, to women, and to children - can be understood in terms of this evolutionary view

Daly & Wilson (1988)• Argued that males will use violence

and threats as strategies to limit their partners autonomy and so decrease the chance of infidelity… – Spousal homicide is common,

especially for women who: •Have left their partners •Have threatened to do so•Have been suspected of planning or

actually committing adultery

Jealous Violence…• Detroit (1972):

– 19% of homicide victims were related to the killer by marriage, compared to 6% who were blood-relatives

• Miami (1980)– 10% of murder victims were marital

relatives, compared to 2% of blood relatives

We mentioned Hans Eysenck’s Theory during class 2…

• Eysenck (1967)– Extraversion-introversion

• Introverts were over-aroused individuals therefore they try to keep stimulation to a minimum

• Extroverts were under-aroused individuals, therefore they tried to increase stimulation

Cortical Arousal Differences

• Eysenck (1967)– He suggests that the difference

between introverts and extroverts depends on the ascending reticular activating system (ARAS)•Causes introverts to be “stimulus

shy”•Causes extroverts to be “stimulus

hungry”

Cortical Arousal Differences• Geen (1984)

– Introverts and extraverts choose different levels of stimulation, but equivalent in arousal under chosen stimulation• Extroverts chose to hear louder noises

than introverts• After put in their chosen environment

their HR’s are the same– This seems to suggest that being at their

preferred level of stimulation results in the same overall level of arousal for both groups

Geen (1984)

• Researcher tested four other groups:– Introverts placed in environment that

other introverts had chosen (II)– Introverts placed in environment that

extroverts had chosen (IE)– Extroverts placed in environment that

other extroverts had chosen (EE)– Extroverts placed in environment that

introverts had chosen (EI)

Geen (1984)

• II = similar HR as free choice introverts

• IE = higher HR than free choice introverts when forced to listen to extroverts’ noise

• EE = similar HR as free choice extroverts

• EI = lower HR than free choice extraverts when forced to

listen to introverts’ noise

Geen (1984)

• Performance on a learning task was also affected:– Introverts did best in introvert-

selected environment– Extraverts did better in extravert-

selected environment•Practical implications:

–Roommates?–Mate Selection?

Eysenck’s Biological Basis of Emotionality

• People who are emotionally unstable are easily aroused in the emotion centers of the brain

• Emotional arousal can cause an increase in cortical arousal

Eysenck’s Biological Basis of Emotionality

• Two important points:– Emotional arousal causes the

behavioral reflections of people to become more apparent

– Emotional arousal sets the stage for conditioning to occur

Are introverts predisposed to anxiety and depression???

• Eysenck says yes…– Conditioning often follows from emotional

reactions– Introverts are more cortically aroused– They are also more emotionally reactive– They have more opportunities for conditioning– Since, conditioning during socialization often

results from punishment and frustration the emotions conditioned are often unpleasant ones

– According to Eysenck, the emotional introverts are highly vulnerable to these disorders

What does Eysenck say about the extraverts?

• The emotional extraverts are less cortically aroused so they don’t condition well

• They don’t learn from punishment so they often show a pattern or poorly socialized and impulsive behaviors

• More likely to suffer from impulse control disorders like pathological gambling, kleptomania, pyromania, etc.

A different view…

• The Behavioral Approach System (BAS)– Responsive to incentives (cues to reward)

and regulates approach behavior – Active BAS produces impulsivity

• Behavioral Inhibition System (BIS)– Responsive to cues to punishment,

frustration, uncertainty, and motivates ceasing, inhibiting, or avoidance behavior

– Active BIS produces anxiety

Sensation Seeking• Marvin Zuckerman (1971)

– Currently, a professor at the University of Delaware

– Defined “sensation seeking” as "a trait describing the tendency to seek novel, varied, complex, and intense sensations and experiences and the willingness to take risks for the sake of the experience"

– These people want to avoid boredom at all costs

Zuckerman (1994)

• Skydivers are characterized with both higher sensation seeking ambitions and a search for thrilling experiences, than most other partakers of other risky activities

• It is claimed that high sensation seekers believe risks to be not as great as do low sensation seekers

• The sensations are also valued less by the low sensation seeker

• An earlier view of psychologists in the late fifties was that skydivers had an inherent death wish

Sensation-Seeking and Drugs

• Zuckerman suggests that the type of sensation seeking may very well determine the forms it will take– For example, those in the lower

socioeconomic classes who are unable to afford the socially acceptable forms instead will be inclined to participate in criminal and antisocial activities such as drug abuse

Sensation-Seeking and Drugs

• Zuckerman is not claiming that all high sensation seekers are likely to desire such substances, however they are more likely to be involved in such activities than those categorized as low sensation seekers

Is there a connection between sensation seekers and psychopaths?

• Impulsive Unsocialized Sensation Seeking– Zuckerman feels that those very high on

sensation seeking may lack the capacity to inhibit behavior that might be detrimental to society

– Trouble inhibiting impulsive action– Thrills at all costs regardless of the

consequences to others– High sensation seekers are less tolerant of

sensory deprivation and they require much stimulation to get to optimal level of arousal•Hebb's theory of optimal level of

arousal applies

Physiological basis for sensation seeking

• Neurotransmitters– Chemicals in nerve cells are responsible for the

transmission of nerve impulse from one cell to another

• Monoamine Oxidase (MAO)– Enzyme that maintains a proper level of

neurotransmitters • Too little MAO = too much neurotransmitter; too

much MAO = too little neurotransmitter – High sensation seekers have low levels of MAO,

producing a need for stimulation to reach the optimal level of arousal

Neurotransmitters and Personality

• Dopamine– Associated with pleasure

• Serotonin– Associated with depression and other

mood disorders • Norepinephrine

– Associated with fight or flight response

Hormones and Personality

Dabbs (1997)– Has studied over 8000 individuals

•Found some interesting correlations between testosterone and behavior

•High testosterone men and women are bolder, more focused, and more rambunctious

– Although most people fall into a middle range, very high testosterone levels can start to be detrimental

High-Testosterone Males

• Characteristics– Lean and balding – Oriented toward action rather than

contemplation– Combative and a bit wild– Has a high libido– Doesn’t smile much– May be unemployed– Tends not to live as long

High-Testosterone Females

• Engage in more extra-marital sex• Smile less than low testosterone

women • Are likely to have more presence • Have a stronger handshake than

low testosterone women

Testosterone and Divorce

• Dabbs also found a correlation between high testosterone and divorce…– Married men have the lowest levels of

testosterone– Single men and divorced men who

are remarried fall in the middle– Divorced men have the highest levels

Convicts or Lawyers?• Dabbs:

– Both socialization and hormones shape the way we are - it’s not just one or the other

– With proper socialization, high testosterone can work to a person’s benefit, as tends to be the case with trial lawyers and actors

– Male prison inmates with high testosterone levels are more likely than other criminals to commit violent crimes and violate prison rules

Criminals and Testosterone• Criminals > Average Men

• Violent Criminals > Non-Violent Criminals

Dabbs & Hargrove (1988)• Suggested a link between high

testosterone levels and crimes of unprovoked violence committed by female prisoners – They measured saliva testosterone

levels in 87 female inmates in a maximum security prison

– The inmates ranged in age from 17 to 60

Dabbs & Hargrove (1988)• Data showed a direct link between

testosterone and aggressively dominant behavior in prison

• Analysis indicated that increasing age is linked to reduced criminal violence and aggressive dominance in female prisoners both directly and indirectly through lower levels of testosterone that come with age

Dabbs & Hargrove (1988)• The researchers note that the five women with the

lowest testosterone were said by prison staff members to be "sneaky" and "treacherous“… – Noting the well-established link between

testosterone and dominance, the researchers suggest:• That when dominant high testosterone

inmates face confrontation, they can act openly and directly

• On the other hand, low testosterone inmates, because they are less dominant, need to be more `sneaky' in dealing with others

Assessment• Biological psychologists feel that

personality derives from the nervous system and the hormonal system– So, why not isolate these areas and

measure it?– Easier said then done but we use the

following:•Electroencephalograms (EEG)•Computer-assisted imaging

– Pet Scans– MRI