3/3/20091Physiological Approaches to PersonalityChapter 7Physiological Measures Commonly Used in Personality Research• Electrodermal Activity (Skin Conductance)• Cardiovascular activity• Brain Activity• Other measures: Biochemical analyses of blood and saliva3/3/20092Electrodermal Activity (EDA):Skin Conductance• Most obtained by electrodes or sensors placed on the skin surface• Advantage: Noninvasive, no discomfort• Disadvantage: Movement constrainedCardiovascular activity• Blood pressure—measure of, e.g., stress reactivity• Heart rate—increases with anxiety, fear, arousal, cognitive effort3/3/20093Cardiovascular activity• Cardiac reactivity– greater than normal increase in blood pressure and heart rate when performing tasks• Cardiac reactivity (and Type A) associated with coronary heart diseaseBrain Activity• Brain spontaneously produces small amounts of electrical activity• can be measured by electrodes on scalp– electroencephalograph (EEG)• Evoked potential technique3/3/20094Brain Activity• Brain imaging techniques—map structure and function of brain– Positron emission tomography (PET)• PET tracks blood flow by using labelled chemicals– Functional magnetic resonance imaging (fMRI)• fMRI monitors the oxygen content of the blood.PET Scan3/3/20095fMRIStructure of the Neuron3/3/20096Structure of the NeuronAt the Synapse3/3/20097Neurotransmitters and Personality• Dopamine—associated with pleasure• Serotonin—associated with depression and other mood disorders• Norepinepherine—associated with fight or flight responseNeurotransmitters and PersonalityCloninger’s Tridimensional Personality Model– Novelty seeking—low levels of dopamine– Harm avoidance—low levels of serotonin– Reward dependence—low levels of norephinepherine3/3/20098Morningness-Eveningness• Being a “morning-type” or “evening-type” of person is a stable characteristic• Due to differences in underlying biological rhythmsMorningness-Eveningness• Many biological processes fluctuate around a 24-25 hour cycle—circadian rhythm; e.g., body temperature, endocrine secretion rates• But wide individual differences are in the circadian rhythm, identified through temporal isolation studies3/3/20099Morningness-Eveningness• Individuals with shorter circadian rhythms hit peak body temperature and alertness earlier in day, get sleepy earlier, than individuals with longer rhythm• Individuals with shorter rhythm tend to be morning persons; individuals with longer rhythms tend to be evening personsMorningness-Eveningness• Morningness-Eveningness Questionnaire• Cross-cultural replication and documentation of stability of characteristic3/3/200910Brain Asymmetry and Affective Style• Left and right sides of the brain are specialized, with asymmetry in control of psychological functions• Using EEG, can measure brain waves, such as alpha wave—an inverse indicator of brain activityBrain Asymmetry and Affective Style• Left frontal hemisphere is more active than the right when a person is experiencing pleasant emotions; right is more active than left with unpleasant emotions• Patterns replicated in adults, children, and