Assigned Reading: Chapter 11. Biological aspects of personality. Skip pages 391-393 [Grey’s model and Cloninger’s biosocial theory].

Study Questions:

1. Discuss the heritability of three personality traits or dimensions. Are each of them relatively high or low in heritability? How is heritability determined? Explain why each of these traits or dimensions might be high or low in heritability.

2. Briefly describe the temperament of three different infants along three dimensions. What would one expect each of these infants to be like as adults?

3. List four aspects of personality that are believed to have evolved in humans. For each, explain why this characteristic has been adaptive in the past and whether it continues to be adaptive today.
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I. Assessing the role of biology in personality

A. Types of biological factors: genes, hormones, anatomy
B. Twin studies traditionally used to study genes
Personality = Shared genes + unshared genes + shared environment + unshared environment
 
C. Heritability of Cattell’s 16PF Traits. Range from high of .75 for concrete vs. abstract thinking and .60 for restrained or sober vs. enthusiastic down to .10 for conservative vs. liberal and relaxed vs. tense.
D. Eysenck’s dimensions assumed to be biologically based.
1. Extraverts have lower levels of arousal than introverts for the same stimulus. Introverts can become overstimulated.
2. Those high in Neuroticism are more easily conditioned to emotional stimuli.
3. Those high in Psychoticism have less control over emotional reactions. More impulsive.
E.  Big Five. Range from .46 for heritability of Openness to .28 for Agreeableness and Conscientiousness.
F. Conclusions about genetic influences
1. From 28 to 46% genetic according to twin studies.
2. Change is possible, even for genetically based traits.
3. Environment affects expression of traits.
4. Model of effects of heredity on behavior:
Genetics -------->

Brain ------>             PERSONALITY ------> Behavior

Prenatal -------->
                                        Hormones

                                ENVIRONMENT

A. Emotional nature of person.
B. General dimensions are Activity level, sociability and emotionality
C. Infancy:
1. Babies differ. "easy" or "difficult" and sociable or shy.
2. Bates: Negative emotionality, positive emotionality, and sensation seeking.
 D. Later life. Associated with 16PF dimensions of shy-inhibited, cool-warm, and reactivity and with all three Eysenck dimensions.
 

A. Measured with self report measures rather than behavior
B. Both positive and negative emotions, as independent feelings.
C. Emotions differ in level of arousal and degree of engagement.
D. Inherited emotions: Anxiety proneness, emotional reactivity, intensity of feelings, sensation seeking, display of feelings
 

A. Based on Darwinian ideas that adaptive traits are more likely to be passed on to future generations.
B. Process of evolution is slow, and previously adaptive traits may not be now.
C. Two basic models in the literature:

1. Traditional. Highly aggressive men most likely to mate. Want lots of partners. Women attract men with youth and beauty and seek best provider.
2. Alternative. In group cooperation, high communication skills, inhibition of impulses, and obedience to authority enhance chances of children surviving.