Chapter 5: Biological Aspects of Personality

Question 1

What is:

evolutionary personality theory

5.1.1 Natural Selection and Functionalism

Answer 1

The application of Darwin’s evolutionary ideas to individual differences. Individual differences and motivations are seen as due to either alternative adaptive strategies or random variation, but it’s difficult to determine the precise causes.

• Regardless, it’s clear that many of our individual tendencies are in our genes.

Question 2

What is:

Angelman syndrome

5.1.2. Angelman Syndrome

Answer 2

A rare genetic condition where children are excessively happy and always filled with glee, but also suffer from mental retardation, sleep very little, and walk with a jerky movement. It’s caused by a defect on chromosome 15.

• Cases like this demonstrate that these syndromes demonstrate that genetic factors can dramatically influence personality.
• The questions remain about the extent to which genes affect personality in normal development and which aspects they shape.

Question 3

What is:

behavioural genomics

5.1.3. Behavioural Genomics

Answer 3

The study of how genes affect behaviour.

• More traditionally, it’s the field that attempts to understand how individual differences in biology affect behaviour.

Question 4

What is:

temperament

5.2. Genetic Effects through Temperament

Answer 4

The stable individual differences in emotional reactivity. Longitudinal development studies suggest that some of this reactivity remains stable over time as children mature.

• e.g. Some babies are cuddly, are quiet, and sleep soundly much of the day. Others are exceptionally active or respond poorly to cuddling and drive their parents insane.
• On a physiological level, people exhibit different nervous system responses to unpleasant stimuli, and these individual response patterns remain stable over time.

Question 5

What are the four basic aspects of temperament?

5.2.1. Activity, Emotionality, Sociability, and Impulsivity

Answer 5

• Activity: Whether you’re more vigorous or passive.
• Emotionality: Whether you’re more easily aroused to anger or fear or other emotions, or calmer.
• Sociability: Whether you approach and enjoy others.
• Aggressive/Impulsive: Whether you’re aggressive and cold or conscientious and friendly.

Question 6

What did Hans Eysenck contribute with his theory of introversion-extroversion?

5.2.2. Eysenck’s Model of Nervous System Temperament

Answer 6

In general, introverts are quiet and reserved while extroverts are active and outgoing. The introversion-extroversion dimension combines elements of the activity and sociability dimensions of temperament. The basic idea is that extroverts have a relatively low level of brain arousal, and so seek external stimulation. On the other hand, introverts already have a higher level of CNS arousal and thus shy away from stimulating social environments.

Question 7

What are the problems with trying to test a nervous system-based theory of temperament?

5.2.2. Eysenck’s Model of Nervous System Temperament

Answer 7

1. It’s difficult to define and measure nervous arousal, since there’s no impartial measure like a thermometer and no single response like a fever.
2. The human body is a system that attempts to maintain equilibrium, meaning that responses rise and fall, varying in baseline, intensity, and duration.

Question 8

What is the evidence that extroverts differ physiologically from introverts?

5.2.2. Eysenck’s Model of Nervous System Temperament

Answer 8

• Studies using electrodermal measures, monitoring the electrical activity of the skin with electrodes.
• Brain Scans
• Introverts are slower to habituate to sensory stimuli, such as unusual tones that are played.

Although this information is interesting and promising, a more complex model of brain arousal and temperament needs to be developed—one that doesn’t rely on one aspect of nervous arousal.

Question 9

What is Pavlov’s classic notion about animals’ nervous systems?

5.2.3. Gray’s Reinforcement Sensitivity Theory

Answer 9

This notion claims that animals’ nervous sytems have evolved to orient them to attractions and dangers, and also emphasizes the importance of reward or punishment. In other words, observation and learning are key to survival.

Question 10

What is the:

behavioural inhibition system (BIS)

5.2.3. Gray’s Reinforcement Sensitivity Theory

Answer 10

This system provides the orienting response to novel situations and things that are punishing. If this sytem is sensitive, then you’re prone to anxiety, always alert and worrying that something bad will happen.

Question 11

What is the:

behavioural activation (or approach) system (BAS)

5.2.3. Gray’s Reinforcement Sensitivity Theory

Answer 11

This system regulates our response to rewards. It’s how we learn to enjoy rewarding activities like good food and friends. If this system is overly active, then you’re prone to be impulsive and constantly seeking rewards. There’s evidence that people whose systems are overactive are more prone to drug addictions and overeating.

Question 12

What are:

sensation seekers

5.2.4. Sensation Seeking and Addiction-Proneness

Answer 12

These people have a consistent tendency to seek out highly stimulating activities (e.g. sky-diving) and are attracted to the unknown.

• They have no consistent preference to whether they enjoy being around others, meaning they’re not simply extroverts.
• Consistent with Pavlov’s original notions, these people have a strong, nervous system-based, orienting response; they’re biologically primed to engage in their environments because they have low levels of internal arousal.

Question 13

What can hemispheric activity tell us about personality?

5.2.4. Sensation Seeking and Addiction-Proneness

Answer 13

​People differ in the levels of neurotransmitters and receptors in different parts of their brains. These differences depend partly on genes and partly on developmental experiences, and yield insight into why we have different motivations and reactions. Relatively greater activtion of the right hemisphere is related to greater reactions of fear and distress in stressful situations.

• Hempispheric activity refers to relative differences in the activation between the right and left cerebral hemispheres in the brain.

Question 14

How did the study of identical twins begin?

5.3.1. Sir Francis Galton

Answer 14

Galton began by tracing eminence through family trees. He noticed that sons of university professors went on to succeed their fathers as professors, and among the lower class hardly anyone achieved eminence. However, it’s not surprising that wealthy people inherit power. Thus, Galton suggested the study of adopted children and adoptive twins.

• One seemingly obvious flaw didn’t jump out at Galton and destroy all his work: the fact that daughters of university professors didn’t follow suit.
• Unfortunately, Galton’s line of thinking is also what led to eugenics.

Question 15

Why are identical twins so similar?

5.3.2. Minnesota Twin Study

Answer 15

There may be patterns of genes that affect our temperaments and behavioural predispositions. When these innate tendencies encounter similar environmental pressures, they often result in similar patterns of behaviour (i.e. personalities).

• Identical twins raised apart from each other have impressive similarities in personality. These similarities are less than those of identical twins raised togehter, showing the influence of nuture. But the similarities of identical twins are greater than that of fraternal twins.

Question 16

Is personality heritable?

5.3.2. Minnesota Twin Study

Answer 16

Personality is partly heritable but not inherited. There are no genes for certain traits or abilities, but there are consistencies that emerge when certain biologically related individuals are raised in certain environments.

• There are certain genes which affect levels of enzymes in the body, some of which are related to behaviours such as anger. However, the gene itself doesn’t cause the behaviour. The gene affects the enzyme, which predisposes the body to act in certain ways, but how the individual does react is determined by the environment, learning, and other aspects of a person.

Question 17

What is:

nonshared environmental variance

5.3.3. Nurture and Nonshared Environmental Variance

Answer 17

The features of the envionment that children raised in the same home experience differently.

• e.g. The first child experiences the second child as their sibling, while the second child experiences the first child as their sibling. Each sibling’s minor daily experiences differ. As a child grows, they begin choosing different environments and are exposed to more varied situations. And so, some aspects of genetic predispositions become more important while others become less important.

Question 18

What is:

epigenetics

5.3.4. Epigenetics

Answer 18

The expression of genes, or the activiation or inactivation of relevant parts of the genome.

• e.g. In times of food deprivation or high stress, the way our bodies make proteins can change, producing long-term differences in us even though our genotype hasn’t changed (i.e. genes can be turned on and off).
• This is one reason that even identical twins can show different rates of mental illnesses such as depression, which have a genetic basis.

Question 19

What have identical twin studies contributed to the study of mental illnesses such as schizophrenia?

5.3.5. Schizophrenia, Bipolar Disorder, Depression

Answer 19

• Many studies have confirmed that schizophrenia tends to run in families; if you have one schizophrenic parent your odds of developing the condition rise dramatically.
• If one has a schizophrenic identical twin, the odds approach 50-50.
• Because of these correlations, some have concluded that schizophrenia is a genetic disease.
• However, many identical twins of schizophrenics never develop the condition. If it is a strictly genetic disease, both twins should develop it all the time.
• MRI scans have also shown that the brain structures between identical twins, one with and one without the condition, differ dramatically. Because identical genes would’ve given identical instructions to the body for brain development, some other factor must’ve contributed to the schizophrenic brain development (or lack thereof).
• Researchers now say that there’s a “genetic predisposition” to schizophrenia.

Question 20

What is the biological evidence for homosexuality being genetic?

5.4. Sexual Identity and Sexual Orientation

Answer 20

• Homosexuality tends to run in families, and monozygotic twins are more likely than dizygotic twins to have the same sexual preference.
• Part of the brain’s anterior hypothalamus, related to sexual behaviour, significantly differs in gay men, and the hypothalamus reacts differently to sexual smells in gays/lesbians versus straight men/women.
• These factors don’t prove that homosexuality has a genetic origin, but it suggests a biological origin for a tendency towards homosexuality.

Question 21

How can homosexuality have been selected through evolution, given that gay people usually have fewer biological children than heterosexuals?

5.4.1. Reproductive Advantage

Answer 21

• One possibility involves kin selection; if the nieces and nephews of gays and lesbians are likely to survive, the genetic tendencies of homosexuality will also survive. Research has failed to support this claim.
• Straight sisters of gay men are especially likely to have more children since they may be especially fertile females. This is called inclusive fitness.
• It could also be the base that gayness somehow confers a direct reproductive advantage to heterosexuals. For example, sickle-cell anemia results in paired recessive alleles, but individuals who are heterozygous don’t have anemia. In this case, the individual has a reproductive advantage and the gene is passed on.

Question 22

How can early hormonal experiences affect personality?

5.4.2. Hormones and Experience

Answer 22

• One study showed that girls who have a male twin brother did better on a cognitive test of spatial ability than girls with female twins. Males generally perform better on this test, so it makes sense that a greater exposure to testosterone during development may have had their brains affected.
• The growth of the brain and the rest of the nervous sytem, a biological factor, is strongly influenced by genes and the (hormonal) environment.
• In analyzing gene-environment interactions, we can’t simply average together the biological and environmental influences to predict personality. We must analyze the uniqueness that results when the two combine.

Question 23

How does Vincent van Gogh demonstrate the effects diseases can have on our personality?

5.5. Mediated Effects of Biology

Answer 23

Vincent van Gogh was quite mad, cutting off his own ear and painting a self-portrait, then committing suicide in 1890. He also had an inner-ear disorder that can produce disabling dizziness, nausea, and auditory disturbances. This was amplified with his personality dysfunction. Illness can cause dramatic effects on our patterns of reactions.

Question 24

How does poisoning affect personality?

5.5.1. Effects through Environmental Toxins

Answer 24

• Mercury poisoning can cause brain damage, making people go mad.
• A significant number of children suffer gradual brain damage traceable to lead poisoning. It impares cognitive function and produces deviant (often antisocial) behaviour.
• Many other metals, including manganese and cadmium, likely affect personality to some degree. People who mine manganese sometimes become compulsive fighters and later develop Parkinson’s disease.

Question 25

What effects does physical illness have on personality? ## Footnote *5.5.2. Effects through Physical Illness*

Answer 25

* Alzheimer's disease causes people to lose their memories, and thus their personalities. * After a stroke, which often damage parts of the brain, people can become aggressive an uncooperative, and sometimes the reverse occurs, depending on which part of the brain is damaged. * In Pick's disease, patients undergo dramatic change in their self of self. Specifically, patients whose right frontal lobe (an area not associated with language) gets damaged will change their beliefs and preferences.

Question 26

What is: **biological determinism** *5.5.2. Effects through Physical Illness*

Answer 26

The idea that people's personalities are determined by their genetics (i.e. you either have "good or bad genes"). * Despite the insights that biology gives us into personality, it would be a mistake to conclude that the frontal lobe is the "ego." * The more complex position is one that acknowledges biological factors as influencers of personality, but still recognizes the individual's capacity to challenge and overcome biological tendencies.

Question 27

How does chronic cocaine use affect personality? ## Footnote *5.5.3. Effects from Legal and Illegal Drugs*

Answer 27

Cocaine tends to produce symptoms of paranoia. Users may become hypersensitive to things like light, noise, and other people. They worry and become obsessed with details, and may become nervous and depressed. Cocaine prevents the reabsorption of dopamine. People who have natural or disease-caused defects in their dopaine systems may be prone to paranoid personalities and susceptible to cocaine addiction.

Question 28

What is: **psychopharmacology** *5.5.3. Effects from Legal and Illegal Drugs*

Answer 28

The study of the role of drugs and other toxic substances in causing and treating psychiatric disturbance. * It must be pointed out that just because a disease runs in the family doesn't mean it's genetic. For example, if the hatter's sons also had manic personality like their father, this wouldn't be a genetic cause, but rather an effect of the mercury continuing to enter the home. * This field, and other fields such as biochemistry, are often far removed from the study of psychology. * As a whole, there is very little research that's been done on the effects of environmental substances and toxins on human personality.

Question 29

What are Sheldon's **somatotypes**? ## Footnote *5.6. Effects from Creation of Environments*

Answer 29

Sheldon's **somatotypology** differentiates three body types: 1. **mesomorphs**: muscular, large-boned atheletes; 2. **ectomorphs**: slender, bookworm types; 3. and **endomorphs**: roly-poly, and supposedly good-natured types. This theory draws from the idea that physique and mental disorders have a relation. However, Sheldon's work wasn't supported by most research.

Question 30

What are some hypotheses for how physiology can affect personality? ## Footnote *5.6. Effects from Creation of Environments*

Answer 30

* The same nervous system that makes one shy and introverted could be the same one that makes one thin. This might be due to high metabolism or a hunger mechanism that's easily satiated. * Social influence may also play a role. For example, anorexics are usually young women who are shy, often harassed, and feel out of control of their situations. * Going through dramatic weight loss will also change things such as resting heartbeat, cholesterol level, blood pressure, etc. any or all of which might affect psychological responses. * If we look a certain way, people will treat us a certain way. For example, students who are thin and "intellectural-looking" may be treated as such by their teachers.

Question 31

What are: **tropisms** *5.6.1. Tropisms*

Answer 31

Environmental forces that push individuals into certain environments. For example, people who are very strong and athletic may seek out certain environments where sports are common and available, and in turn these environments shape a "sports personality." * Some of these forces originate in temperamental differences, which come from genetics, hormonal exposure, and early experiences. * Other forces are environmental, as punishments and rewards push and pull people into different life paths. * It's often incorrect to think of personality as randomly encountering various stressful or unstressful events, as our temperaments can often shape our environments.

Question 32

How can biological influences on the creation of environments affect personality? ## Footnote *5.6.1. Tropisms*

Answer 32

For example, some individuals with a particular DNA sequence are especially sensitive to smelling the compound ionone and may be especially arttracted to tomatoes and certain Pinot Noir wines. They might love a pizza bistro while their friends find it repugnant. These biological predispositions will lead an individual to be attracted to certain environments and activities that could in turn have systematic influences on personality.

Question 33

What is the physical attractiveness stereotype? ## Footnote *5.7.1. Physical Attractiveness Stereotype*

Answer 33

Many people expect physically attractive others to do good and to be good, i.e. "what's beautiful is good." Thus, physically attractive people tend to be happier, although they may suffer more if they lose their attractiveness as they age. Similarily, there are more positive expectations for children with the culturally "desirable" characteristics.

Question 34

What is: **sociobiology** *5.8. Sociobiology*

Answer 34

The scientific study of the influence of evolutionary biology on an organism's responses regarding social matters. This field looks at the reasons for (the functions of) the evolution of animal social behaviours, such as sexual fidelity. * These analyses work well on simple, instinct-driven animals, but become complicated when applied to humans. For example, the colourful plumage of peacocks is integral to attracting mates, but it would be a gross oversimplification to say that people wear fancy clothes for this same reason. * This type of analysis is commonly applied to human aggression, courtship, and familyrelations, since these are the prime focus of evolutionary biologists studying other organisms.

Question 35

To what extent are our social norms rooted in ancient pressures for survival? ## Footnote *5.8.1. Cinderella Effect*

Answer 35

There is evidence to show that one's stepchildren are, on average, treated worse than one's genetic children. Sociologists suggest that this Cinderella phenomenon may have resulted from natural selection, in which parents have evolved to give preference and protection to their biological children. In general, families may have an innate predisposition to defend themselves and their territories. This analysis is interesting, but we must not ignore the influences of human learning and culture on behaviour.

Question 36

What is the true meaning behind Darwin's theory of "survival of the fittest"? ## Footnote *5.9. Darwinism and Social Darwinism*

Answer 36

Many often incorrectly assume that this theory means we live in a "dog-eat-dog" world in which it's "every man for himself." This in fact is not implied by evolution, and isn't what Darwin proposed. In complex societies such as that of primates, what evolves is a *capacity* for certain types of behaviour in certain situations. We'll never find a simple gene that leads directly to a behaviour. * Additionally, many make the mistake of thinking that the "fittest" individual is the one who can out-produce others, and they also wrongly assumed that the fittest culture is the one that can conquer others (**Social Darwinism**). * This biological principle is often changed into a moral imperative and interpreted to mean that weak creatures and cultures *shouldn't survive*.

Question 37

What are some common societal errors and biases about the nature of personality? ## Footnote *5.9.1. Culture, Nazis, and "Superior Races"*

Answer 37

* There is evidence that people from other cultures differ systematically from each other, but there's little evidence that these differences are genetically based. When immigrants move to the US from Asia, Africa, Europe, or Latin America, their children tend to behave more like the people of the new culture than the cultures of their parents. * Even educated people are attracted to the idea that "other" people are inherently inferior and therefore less deserving of freedom, success, and even life. * In the case of Hitler and the Nazis, the inferior subhumans were Jews, Gypsies, homosexuals, and those with disabilities. Many physicians helped lead the way to mass murder.

Question 38

What is the: **human genome project** *5.9.2. The Human Genome and Eugenics*

Answer 38

* An effort to identify the functions of each of the 20,000 or so genes. The immediate goal is to develop treatments for inherited diseases. However, genes (or patterns of genes) that influence people's propensities to be aggressive or depressed, or intelligent or shy, and so on are increasingly being discovered. * Increasingly, there is the idea that since modern medicine has reduced the need for evolutionary advantages, geneticists should now turn to preserving the healthy gene pool. There's no evidence that the human gene pool is deteriorating. Indeed, people are getting taller, stronger, and live longer than ever before. * If we were to use genetic engineering, what defects would we "fix"? How would you feel if someone close to you decided to undergo this work? What if your child's teacher recommends fixing your child's unruly behaviour?