Week Six Notes
Week Six Notes Psyc 287
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This 11 page Class Notes was uploaded by Ashley Choma on Friday September 30, 2016. The Class Notes belongs to Psyc 287 at University of Nebraska Lincoln taught by Dr. Pearce in Fall 2016. Since its upload, it has received 10 views. For similar materials see Psychology of Personality in Psychology at University of Nebraska Lincoln.
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Date Created: 09/30/16
Psychology of Personality PSYC 287 Week Six Notes 9/27 Chapter 9 Reading Chapter 9: The Inheritance of Personality: Behavioral Genetics and Evolutionary Psychology Behavioral genetics addresses how traits are passed from parent to child and shared by biological relatives Evolutionary psychology addresses how patterns of behavior that characterize all humans may have originated in the survival value these characteristics provided over the history of the species Behavior Genetics o A pattern of behavior that is generally consistent across situations is a personality trait o Controversy Eugenics: the belief that humanity could and should be improved through selective breeding Cloning: the belief that it might be technologically possible to produce a complete duplicate – psychological as well was physical – of a human being Research on genetic bases of behavior might lead the public to think that outcomes such as intelligence, poverty, criminality, mental illness, and obesity are fixed in one’s genes rather than changeable by experience or social circumstances o Calculating Heritability To the degree that a trait is influenced by genes, people who are closer genetic relatives ought to be more similar on the trait than people who are more distantly related Twins – monozygotic (identical); dizygotic (fraternal) Behavioral genetics concentrates on the less than 1% of the human genome that commonly varies across individuals Heritability coefficient – computed to reflect the degree to which variance of the trait in the populations can be attributed to variance in genes In the case of twins, one simple formula is: heritability quotient = (rMZ –rDZ) x 2 An alternative way is to calculate similarities in personality across relatives other than twins o What Heritability Tells You Genes matter Insight into effects of the environment Growing up together in the same home does not tend to make children similar to each other o What Heritability Can’t Tell You Nature vs. Nurture Heritability calculations do not solve the nature- nurture debate Nature-heredity; nurture-upbringing and environment o Molecular Genetics New research seeks to unravel the mystery of how specific genes influence life outcomes by diving into the actual DNA A gene called DRD4 affects the development of dopamine receptors Alleles-variants No single gene accounts for more than a race of the variance in personality o Gene-Environment Interactions How people choose their environment (niche picking) People tend to select and even create environments that are compatible with and may magnify their genetically influenced tendencies o Epigenetics Even at a biological level, the effect of a gene on behavior may depend on more than the gene itself Recent work on epigenetic has begun to document how experience can determine how or even whether a gene is expressing during development Transactions between genes and the environment can go in both directions and can reinforce or counteract each other o The Future of Behavioral Genetics Better understanding of the gene-environment correlations and interactions involved in personality development, and exploring for the genes that are associated with personality Genome-wide association (GWA) Evolutionary Personality Psychology o Evolution and Behavior Evolutionary theorizing beings with this recognition: every human being is the latest in a long, unbroken chain of winners Aggression and altruism A tendency to be aggressive can lead to negative outcomes (altruism) a tendency to aid and protect other people, especially close relatives, might help ensure the survival of one’s own genes into succeeding generations, an outcome called inclusive fitness self-esteem according to the “sociometer theory” feelings of self- esteem evolved to monitor the degree to which a person is accepted by others (Mark Leary) depression different kinds of depression have different causes o social loss – pain, crying, and seeking social support o failure – fatigue, pessimism, shame, and guilt mating behavior particular differences stand out in: o mate selection and attraction – what one looks for in in the opposite sex o mating strategies – how one handles heterosexual relationships Attraction o Men are more likely to place higher value on physical attractiveness; women are more likely to value economic security in their potential mates Mating strategies o According to the evolutionary account, men want more sexual partners than women do, and are less faithful to and picky about the women with whom they will mate Sociosexuality: the willingness to engage in sexual relations in the absence of a serious relationship Jealousy o “sexy son hypothesis” – proposes that a few women consistently - & many women occasionally – follow an atypical reproductive strategy o the theory is that if they produce a boy, even if the father then leaves, the son will be just like his dad o Individual Differences Adaptation At the level of the species, a trait that used to be maladaptive or just irrelevant can suddenly become vital for survival An individual difference variable that may encompass both kinds of adaptation is called “life history” Accounting for individual differences 3 different ways: o behavioral patterns evolved as reactions to particular environmental experiences o people may have evolved several possible behavioral strategies, but actually use the one that makes the most sense given their other characteristics o some biologically influenced behaviors may be frequency dependent, meaning that they adjust according to how common they are in the population at large o Five Stress Tests for Evolutionary Psychology Methodology It is unwise to assume that every genetically influenced trait or behavior pattern exists because it has an adaptive advantage Reproductive Instinct Evolutionary psychology’s assumption that everybody wants as many children as possible seem strange in a world where many people choose to limit their own reproduction Conservative bias Human flexibility Evolutionary accounts seem to describe a lot of specific behavior as genetically programmed into the brain Biological determinism or social structure/ People evolved to be flexible o The Contribution of Evolutionary Theory Not every aspect of thought or behavior exists because it is specifically evolved 9/27 in class notes Chapter 8 Continued What have we learned? o Ascending reticular activating system – controls the amount of stimulation the brain is receiving In introverts, ARAS allows relatively more stimulation, which causes withdrawal behavior/negative reaction In extraverts, ARAS allows relatively less stimulation, causing person to crave more o The amygdalae influence both positive and negative emotions Active amygdalae in shy, anxious people when exposed to strangers Also active when people are exposed to pleasurable stimuli Conclusion: the amygdalae play a role in judging whether stimulus is threatening or rewarding (Barrett, 2006) An active amygdala causes different effects in people high in different big five traits In extraverts, it responds to positive stimuli In neurotics, it responds to stimuli that cause emotional conflict Affects motivation (Charles Whitman shootings) o Frontal lobes are involved in higher cognitive functions (planning, analyzing) o Left frontal lobe activity is associated with emotional stability, approaching pleasing things, and muting reactions to unpleasant things o Right frontal lobe activity is associated with withdrawal and neuroticism (but injury causes failure to positive emotional response – Capgras syndrome, pgs 274-275) o Phineas Gage and other similar cases: Impaired judgment, lack of emotion, lack of regulation Somatic marker hypothesis (pg 274) – because emotions are so vital to personality o Prefrontal Cortex Active (along w/ other structures) when cooperating Especially active in people prone to negative emotions around others o Anterior cingulate Connection with amygdalae suggests involvement in controlling emotional responses and inhibiting impulsive behavior Possibly involved in processing unexpected stimuli o Posterior cingulate Threat response, spatial processing o Brain Systems Sets of structures involved in reflective thinking about self (c-system), effortless thinking about social situations (x- system) p.279 Interactions between parts may be more important than individual parts of brain Table 8.1 in the book – know things we have discussed Neuron Firing o Can be caused by several stimuli: Pressure, temperature, neurotransmitters o Stimulus causes ion channels within the cell membrane to open o Flow of ions through cell membrane changes… o Neurotransmitters o Synapse: space between axon of one neuron and dendrite of adjacent neuron o A neuron receives as many as 15,000 connections from other neurons o Neurotransmitters Are released by bioelectrical impulse They enter the synapse And cause or suppress firing of adjacent neuron o Dopamine Involved in brain’s control of body Involved in approach response Shortage in left hemisphere = lower novelty seeking Shortage in right hemisphere = increased harm avoidance High levels correlate with sociability (and perhaps extraversion, impulsivity) Also activity level, alertness Parkinson’s disease (tremor, motor impairment) caused by lack of dopamine Reward deficiency syndrome: a defect in dopamine receptor gene is associated with lack of sufficient number of dopamine receptors This prevents normal neurochemical reward cascade The inability to produce feeling of well-being often results in “self-medication” (alcohol, nicotine, stimulants, drugs, junk foods, gambling, porn) Not clear whether number of dopamine – responsive neurons is entirely genetic or influenced by experience (rewarding, experiences may increase development of dopaminergic portions of nervous system) Interacts with nucleus accumbens to form part of Behavioral Activation System (which produces and reinforces motivation to seek rewards) Dopamine seems to be associated with extraversion and openness to experience o Serotonin Involved in inhibiting impulsive behaviors, restraining overreactions, limiting worrying Low levels found in violent criminals and suicides Prozac inhibits serotonin reuptake, leaving higher levels in the nervous system Associated with increase in extraversion and decreased neuroticism o Dopamine is associated with extraversion and openness to experience o Serotonin is associated with conscientiousness, agreeableness, and emotional stability Hormones o Produced in central location and affect cells throughout the body o Epinephrine (adrenaline) Stress response (fight or flight) Female stress response may differ substantially o Norepinephrine (noradrenaline) Increases heart rate, concentration High levels associated with anxiety o Testosterone Males who regularly engage in aggressive behavior, drug abuse, and have problems with interpersonal relationships tend to have high levels of testosterone Converse is not necessarily true: high levels of testosterone are not associated with aggression Female prisoner who committed unprovoked violent crimes had higher testosterone levels than other female prisoners Injections of testosterone increase sexual desire in women o Cortisol Stress, depression, and anxiety can cause an increase in cortisol Increases associated with immune suppression, increase in blood sugar, aid in metabolism Sustained increases can cause heart disease, muscle vesting, damage to cells in hippocampus (impaired learning, memory retrieval) Low levels associated with PTSD, sensation seeking, reduced response to danger or stress o Oxytocin Released by the hypothalamus Role in romantic attachment, sexual response, parental attachment Behavioral correlates in women: Increases observed during sexual activity, childbirth, breastfeeding Behavior correlates in men and women Reduced fear response Caffeine o Stimulant o Reduces effects of adenosine in the brain Adenosine is an inhibitor neurotransmitter that suppresses activity in the central nervous system Also may be involved in control of sleep-wake cycle Accumulation of adenosine may be responsible for sleepiness o Secondary effects on most all neurotransmitters o Increases circulating epinephrine Methamphetamine o Highly addictive Activates the neurochemical reward cascade/dopamine release o Physical effects Hyperactivity, sweating, headache, etc. o Psychological effects Euphoria, anxiety, alertness, increased energy, etc. o Neurotoxic to dopamine neurons in midbrain o Associated with risk of Parkinson’s disease o May cause persistent or permanent memory loss, reduced attention span o Effects on neuron may cause withdrawal Alcohol o Increases effects of inhibitory neurotransmitter GABA Causes motor impairment, slurred speech o Inhibits excitatory neurotransmitter glutamate Causes physiological slow down o Increases amount of dopamine o Cerebral cortex: depresses inhibition, slows sensory processing, inhibits thought o Cerebellum: affects sexual arousal and performance o Medulla oblongata Cannabis (THC) o Analgesic effects, relaxation, sensory alteration, fatigue, appetite stimulation (via hypothalamus) and dopamine release (reward) suppresses nausea 9/29 in class notes Behavior Genetics and Evolutionary Personality Theory – Chapter 9 Chapter 8 continued Clinical vs. cosmetic alteration of brain/body chemistry o “performance enhancing drugs” more socially acceptable than Prozac – caffeine Ethics of Cosmetic Psychopharmacology o Is it wrong for a salesperson without psychological deficits to alter brain chemistry to gain competitive advantage? o Loss of moral capacity – get credit for the way we are, for the good things that we do Chapter 9 Behavioral genetics and evolutionary biology o Behavioral genetics focuses on the study of the heritability of aspects of personality that differ from one person to the next Heritability of personality o Evidence suggests personality traits of identical twins (.60), fraternal twins (.40), non-twins (.20), and adopted siblings (.05) correlate at magnitudes proportional to genetic similarity, which suggests heritability Heritability vs. Family Environment o Attention deficit hyperactivity disorder is inherited o Many other forms of childhood and adolescent mental illnesses appear to be related to family environment (anxiety, depression) o Family environment also appears to influence many behaviors and traits o B-data and s-data provide different results in heritability studies o B-data show more similarities in siblings raised together, which suggests family environment plays a role Heritability vs. Environment o Heritability and environment can both be causes of impairments Moderate mental retardation seems to run in families Severe mental retardation does not, suggesting environmental cause Heritability Coefficient o Find correlation of identical twins’ personality trait of interest o Find correlation of fraternal twins’ personality trait of interests o Calculate difference and multiply by 2 Example” assume MZ twins correlate on trait x measure at .70 and DZ twins correlate on the same measure at .30 .70-.30 = .40 .40 x 2 = .80 trait x’s heritability coefficient is .8- notice that if the correlations for MZ twins on the trait of interest are not very different from DZ twins on the trait of interest, the heritability coefficient will be low examples 2: assume MZ twins correlate on Trait Y at . 50 and DZ twins correlate on Trait Y at .45 o .50-.45 = .05 o .05 x 2 = .10 this means that heritability coefficient depends on variability zero correlation problem o if the trait you are interested in doesn’t vary much, heritability coefficient approaches zero o doesn’t necessarily mean trait is not inherited text’s example of heritability of two arms (page 309) Molecular genetics o Studies mostly reveal only that a given gene is possibly associated with certain behavior o Studies commonly use the associated (or correlation) research design o Other examples: DRD4 is a gene that encodes dopamine receptors Different expressions of this gene affect dopaminergic systems, which in turn affect reward response, sensation – seeking, impulsivity 5-HTTLCPR is a gene that codes for the protein that transports serotonin one variant of gene has been found in some studies to be associated higher with neuroticism, anxiety, and stronger amygdala response to stress but effect sizes are very small and cannot be replicated readily Gene-environment interaction studies o Capsi and Moffitt: Found that unfavorable version of 5-HTTLPR was associated with depression in response to stress However, this finding is very hard to replicate o Capsi: A gene on X-chromosome is associated with enzyme MAOA, which effects functioning of several neurotransmitters, and low MAOA was associated with antisocial behavior in maltreated boys Again, this hasn’t been replicated Replicated – 35% antisocial behavior (not 85%) Conclusions o Very little is known with any significant degree of confidence o Nature vs. nurture (heredity vs. environment) is not often a useful framework due to complex interactions o Knowing genotype might help a person minimize susceptibility to environmental risks But isn’t it always advisable to avoid child abuse, poverty, etc. if possible?
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