3 TemperamentIndividual differences in general mood or quality of emotional response that are moderately stable, inherited, and biologically based
4 Inhibited versus Uninhibited Children (Kagan, 1994) Reacts to unfamiliar people and situations with avoidance, distress, restraintTakes longer time to relax in new situationsHas more fears and phobiasIs timid and cautiousUninhibitedReacts to unfamiliar situations with spontaneity and joyTakes shorter time to relax in new situationsHas fewer fears and phobiasIs not restrained in new situations
5 Kagan, Arcus, & Snidman (1993) At 4-months,Videotaped behavior during familiar and novel stimuli (voices, mobiles, balloons)Rated infants on reactivity (body movement, crying)At 14-months, 21-months, 4.5 years, 8 yearsVideotaped behavior and monitored physiology
6 High vs. Low Reactive Infants (Kagan et al., 1993) High reactiveShow greater fearful behavior, heart rate acceleration, increased blood pressureSmiled and talked less with unfamiliar adultWere shy with unfamiliar peerVaried within groupLow reactiveShowed lesser fearful behavior, heart rate acceleration, increased blood pressureSmiled and talked more with unfamiliar adultWere less shy with unfamiliar peerVaried within group• high reactive defined as high movement + high crying at time 1• according to Kagan, about 15% of extremely reactive babies remain fearful and the rest become normal. None become fearless or extraverted• study of 31 fetuses -- monitored on multiple occasions -- high fetal activity levels associated with increased difficulties, unadaptability, and unpredictability after birth
7 HEMISPHERE ACTIVATION Left HemisphereApproach-related emotionArousal -> happiness, resilience in the face of stressUnderarousal -> vulnerable to sadness and depressionRight HemisphereWithdrawal-related emotionArousal -> fear, disgust, anxietyUnderarousal -> relaxation
8 HEMISPHERE ACTIVATION Davidson’s Evidence from EEGReliable from one month to another (r = .66)More right-sided activation and more intense negative and less intense positive trait moodMore right-sided activation and more intense negative affect in response to film clips meant to elicit fear and disgustInfants who cried when separated from their mothers had higher right-sided activationInhibited toddlers had low left-sided activationPeople with greater left-sided activation had more natural killer cell activity
9 Different ways of estimating genetic influence: Behavioral GeneticsDifferent ways of estimating genetic influence:Experimental animal studiesTwin studiesAdoption studies• show the giggle twins• animal studies -- how characteristics hold up over generations (e.g.: breeding fruit flies) -- what traits can you breed in?• twin and adoption studies attempt to compare the variations between people with varying degrees of genetic relatedness• both are attempts to “account for observed variance” by partitioning into genetic and environmental contributions
10 Heritability Twin studies: Compare identical twins reared together with those reared apartAssume the similarity between “Together” twins due to shared genes and environmentAssume the similarity between “Apart” twins due only to genesTHEN:“Similarity of together” - “Similarity of Apart” = environment, and 1- environment = genes• What’s wrong with this over-simplified logic?• adoptive studies use similar logic -- are adopted children more like their biological or their adoptive parents? If similar to biological we assume big genetic contribution, if similar to adoptive we assume big environmental
11 Heritability Another form of twin study: Compare monozygotic (MZ) together twins with dyzygotic (DZ) together twinsAssume similarity of MZ due to genes and environmentAssume similarity of DZ due to 1/2 genes and environment
13 HeritabilityHeritability is an estimate of the percentage of the variance in a particular characteristic in a particular study that resulted from genetic variation in that study.
14 Variance********• when we explain variance we are explaining why everyone in our sample did NOT get the same score73510FriendlinessVariance = ((1-5)2 + (3-5)2 + (3-5)2 + ….. (10-5)2) / N-1“ Average deviation”
15 HERITABILITY 30% 60% 0% Why is “gene” only circle impossible?? Example: Identical twins, different pairs have fairly different backgrounds30%EnvironmentGenesExample: Identical twins, different pairs havevery similar backgrounds60%GenesEnvironmentExample: Cloned people rearedin very different situations• explain that the circles in diagram represent variance between people as a group - NOT between individuals - and that it is variance in a particular variable (eg: trait)• note that heritability estimates depend on how much variance in genes or environment that there is to be explained in that population - dividing up variance, therefore all the components must add up to one. Sometimes only genes and environment considered, sometimes their interactions as well• note that it doesn’t matter whether it’s twins or not, since the variance will be across the entire sample (twins become like a single data point and it is there difference from other twins that matters)• Note that typical twin studies are like the second situation, therefore heretibility estimates large. If they were more like first circle, ie reared in very different social situations, then heretibility estimates would be smaller.* Why is a gene only circle impossible? - No such thing as identical environments across the lifespan.0%EnvironmentWhy is “gene” only circle impossible??
16 HERITABILITY IS NOTThe chance that an individual will have a certain characteristicHow much influence genes or environment have on an individual personThe absolute influence of a gene outside the particular environment in which the estimate was made
17 Heritability is:an estimate of the percentage of the variance in a particular characteristic in a particular study that resulted from genetic variation in that study.
18 HERITABILITY Some results from the major twin studies: Intelligence – H = 30% - 70% (some specific cognitive abilities are more heritable than others)Activity level, emotional reactivity, sociability-shyness – H = 20% - 50%Neuroticism, extraversion, impulsivity, monotony avoidance – H = 23% - 45%Depression – H = 13% for male relatives and 30% for female relativesVocational interests – H =0.43Religiosity – H =0.49Traditionalism – H =0.53Attitudes toward drinking alcohol – H = 51%Radicalism and toughmindedness – H > 50%Aggressive, antisocial, criminal behavior – H about 50%
19 Schizophrenia and Heritability Twin studies:0% concordance in identical twins and 6% concordance in fraternal twinsAdoption Studies:1%3%9%17%Not SSAdopted FamilyBiologicalFamily• cell entries are percentage of children who develop schizophrenia• population average is 1%• Note that this is a perfect example of the idea of “interaction effects”
20 THE “NATURE-NURTURE” DEBATE A devil, a born devil, on whose natureNurture can never stick; on whom my painsHumanely taken, all, all lost, quite lost-The Tempest• The debate is not new….• What does the quote mean?
21 NATURE AND NURTURE INTERACTIONS A Central Theme in Personality and Social PsychologyThe dynamic interaction between the person and the situation. People come into the world with some predispositions. They act in accordance with these predispositions and get reactions and feedback from the environment. These reactions and feedback, in turn, inform, drive, and even determine their behavior in the future. The cycle continues.• remind them of our personality versus situation discussion earlier• this can be mapped onto the nature (personality) versus nurture (situation) debate
23 NATURE AND NURTURE INTERACTIONS Continuity of Behavior: Two Hypotheses(Caspi, Bem, & Elder, 1987)The data on children who tantrum:Men: downward occupational mobility, erratic work lives, more likely to divorceWomen: married men with lower occupational status, more likely to divorce, ill-tempered mothers
24 NATURE AND NURTURE INTERACTIONS Continuity of Behavior: Two HypothesesCumulative continuityWe make certain choices, deliberate or not deliberate, that determine what direction our life goesInteractional continuityEarly temperament forms an interactional style that evokes reciprocal, maintaining responses from others. The person acts, the environment reacts, and the person reacts back.
25 MAIN POINTSPersonality comes from a complex dynamic interaction of nature and nurtureNature contributes to personality through genetics, as well as basic processes such as brain activation, temperment, neuroanatomy, and biochemistry.Nurture contributes to personality through influences such as parental relationship, sibling competition, environmental stimulation, and culture.Nature and nurture interact from the fetus throughout the life span. Diathesis, cumulative continuity, and interactional continuity are some of the mechanisms through which these interactions occur.• follow this with case-study exercise in building interactional models
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