Psychology 305 1

Psychology 305A: Theories of Personality

Lecture 7

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Scoring Your Questionnaire: EAS

1. Reverse score items 6, 18, and 19.

2. Sum the following items:

• 2, 7, 10, 17 • 1, 6, 15, 20 • 5, 8, 13, 18 • 4, 9, 11, 16• 3, 12, 14, 19

3. Divide each sum by 4.

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1. What hypotheses has the evolutionary approach generated regarding (a) sex differences in jealousy (continued) and (b) birth order and personality?

The Biological Perspective

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2. What are the goals of behavioural genetics?

By the end of today’s class, you should be able to:

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1. review research supporting evolutionary hypotheses related to sex differences in jealousy.

3. describe the “principle of divergence.”

2. discuss the influence of birth order on the Big 5.

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5. review the goals of behavioural genetics.

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4. discuss criticisms of the evolutionary approach.

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What hypotheses has the evolutionary approach generated regarding sex differences in jealousy? (continued)

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• Following from these adaptive problems, evolutionary psychologists have generated 2 interrelated hypotheses regarding sex differences in jealousy:

Hypothesis B: Males are more likely than females to become jealous in response to cues that suggest sexual infidelity.

Hypothesis A: Females are more likely than males to become jealous in response to cues that suggest emotional infidelity.

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• Studies that have tested these hypotheses include:

Buss et al. (1992; see also Buunk et al., 1996; Miller & Maner, 2009; Schutzwohl & Kock, 2004):

Presented participants with the following dilemma:

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Think of a serious, committed romantic relationship that you had in the past, that you currently have, or that you would like to have. Imagine that you discover that the person with whom you’ve been seriously involved has become interested in someone else. Of the following, what would distress or upset you more?

1. Imagining your partner forming a deep emotional attachment to that person.

2. Imagining your partner enjoying passionate sexual intercourse with that other person.

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Results consistent with Hypotheses A and B.

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Buss et al. (1999)

Had participants imagine that their partners had become both sexually and emotionally involved with someone

else.

Asked participants to indicate which aspect of the infidelity they found more upsetting.

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Consistent with Hypotheses A and B, found that:

(a) 63% of the males but only 13% of the females reported that the sexual aspect of the infidelity was most upsetting.

(b) 87% of the females but only 37% of the males reported that the emotional aspect of the infidelity was most

upsetting.

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In a large-scale cross-cultural investigation, Brase, Caprar & Voracek (2004) found similar sex differences in China, Germany, the Netherlands, Korea, Sweden, Japan, England, and Romania.

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Pietrzak et al. (2002) replicated findings regarding sex differences in jealousy using physiological measures (e.g., measures of heart rate, skin conductance; assessment of facial expression).

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What hypotheses has the evolutionary approach generated regarding birth order and personality?

• Most animals, including humans, require some degree of parental investment (i.e., investment of parental resources) in order to survive.

• When parents have more than one offspring, siblings must compete for parental investment.

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• Evolutionary psychologists maintain that first-born children (FBs) and later-born children (LBs) have developed different strategies to maximize parental investment.

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• E.g. of strategies used by FBs in non-human species:

Predatory birds confronted by a scarce food supply: Older chicks attempt to peck younger chicks to death or exclude them from the nest.

Cuckoo birds: First chick to hatch attempts to eject all other eggs from the nest.

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• For humans, evolutionary psychologists have generated several hypotheses regarding the strategies that FBs and LBs use to maximize parental investment and the impact that these strategies have on personality:

Hypothesis A: FBs are higher in extraversion than LBs.

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Hypothesis B: LBs are higher in agreeableness than FBs.

Hypothesis C: FBs are higher in neuroticism than LBs.

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What are the goals of behavioural genetics?

• Goal 1: To determine the degree to which individual differences in personality characteristics are caused by genetic factors as opposed to environmental factors:

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VP = VG + VE

VP = Variation in an observable personality characteristic within a population.

VG = Variation in the genetic factors that contribute to that characteristic.

VE = Variation in the environmental factors that contribute to that characteristic.

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• Goal 2: To identify the genetic factors that contribute to individual differences in specific personality characteristics.

E.g., the gene D4DR on chromosome 11 contributes to individual differences in “sensation seeking” (also referred to as novelty seeking).

• Goal 3: To identify the environmental factors that contribute to individual differences in specific

personality characteristics.

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1. What hypotheses has the evolutionary approach generated regarding (a) sex differences in jealousy (continued) and (b) birth order and personality?

The Biological Perspective

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2. What are the goals of behavioural genetics?