Psych 301 10 3 3 Personality What is the biological basis of personality Nearly all personality traits have a genetic component Twin studies show approximately half the variance in personality is explained by genetic similarity Identical twins become more alike as they grow older This is not true for siblings and dizygotic twins Family environment Shared home environment has limited impact on personality Adopted children have no significant personality relationship to adoptive parents Larger but still small relationship between adoptive children and biological parents Birth order is related to personality Particular parenting style may not have a major impact on personality Temperaments are evident in infancy Temperament Biologically based tendencies to feel or act in certain ways Three temperament dimensions A Buss Plomin Activity level Emotionality Sociability Two temperament dimensions Rothbart Reactivity Self regulation Types based on temperaments Three temperament styles Chess Thomas Easy children well adjusted Difficult children undercontrolled Slow to warm up children inhibited About 60 of children fall into these types Other 40 are combinations New Zealand study Classification at age 3 predicted later personality and behavior Neurophysiological mechanisms Eysenck s theory Cortical arousal is regulated by the ascending reticular activating system ARAS We seek an optimum level of arousal Extraverts Chronically underaroused Seek stimulation Introverts Chronically overaroused Seek calm More recent work Gray s Approach inhibition model of learning Extraverts have stronger BAS Introverts have stronger BIS BIS is associated with frontal lobe activity Extraverts have more active dopamine circuits involved in BAS Functional approaches to personality Big 5 each provide important info for mate selection D Buss Problem natural sexual selection should have eliminated variation Traits not evolutionarily relevant Social equilibrium some traits more valuable when rare no univeral optimum depends on peers selection creates balance among types Can personality change Traits remain stable over time Most research shows traits to be very stable over time Big Five study shows stability but consistency increases as individuals get older Stability is in terms of ranking of individuals not absolute scores People tend to become more agreeable and more conscientious as they get older This pattern holds across cultures Characteristic adaptations change McCrae Costa model Basic tendencies Dispositional traits determined by biological processes Characteristic adaptations Adjustments people make to situational demands Different aspects of personality stable and fluid interact to produce behavior Three levels of personality Stability of personality dependent on level at which you view it Quantum change Transformation of personality that is sudden profound enduring and affects a wide range of behavior Appears to happen without effort Plays central role in life narratives Brain injury and personality change Damage to specific brain regions can lead to personality changes Frontal lobe damage can cause people to become more extraverted impulsive socially inappropriate and moody Temporal lobe damage can cause a person to become humorless obsessive paranoid and rule bound Alzheimer s disease can cause a variety of surprising personality changes Drugs and personality change Serotonin enhancing drugs can cause significant personality changes Decrease in neuroticism Increase in extraversion Independent of effects on depression SSRI study Non depressed participants Reduction in hostility Increase in cooperative behaviors
View Full Document
Unlocking...