Lecture 7 – Physiological Approaches to Personality
Researches focus on distinct physiological systems such as heat rate or brain waves; the typical research
question posed by contemporary psychologists concerns whether some people will exhibit more or less of a
specific physiological response than others under certain conditions; ex. Are shy people more likely to show
high levels of anxiety?
Requires specific conditions (audience) under which a specific personality characteristic (shyness) will produce
a physiological indicator (heart rate.)
Audience + Shyness anxiety behaviour
Physiological Measures Commonly Used in Personality Research
Electrodes: most common of measures; senors placed on surface of skin; drawback – participant is wired to
recording machine (polygraph) so movement is constrained.
Telemetry: electric signals are sent from the participant to the polygraph through radio waves instead of
wires; being used on astronauts.
ELECTRO DERMAL ACTIVITY
Sympathetic nervous system: branch of the autonomic nervous system that prepares body for action (flight or
fight); sweat glands on palms of hands or feet are controlled by this.
Before the sweat is visible, it can be detected through electricity, since water conducts electricity; skin
conductance allows researchers to monitor sympathetic nervous system activity.
Can be elicited by all sorts of stimuli: sudden noises, emotional pictures with charged content, conditioned
stimuli, mental lie detector test; some people show skin conductance with no stimulants present; a person
who is rated high in anxiety is likely to have a nervous system that is in a state of chronic activation.
SELF INJURY STUDY
Emotional Reactivity: intensity and persistence of emotion in response to stimuli; thought to be elevated
among those who self-injure, particularly those with negative events/stressful tasks; included stress in 2
groups and measured skin conductance.
Group 1: Individuals w/history of self-injury Group 2: Individuals w/o history of self-injury
Stress induction: matching game in which failure feedback is given even when a response is correct.
Goal: determine how long people stay in the game and tolerate the distress of negative feedback.
Findings: individuals with history of self-injury have elevated skin conductance and more negative emotional
reactivity to stress; individuals who self-injure quit the game sooner which may indicate lower distress
Implication: emotional reactivity and distress tolerance may be key to understanding self-injury.
Cardio vascular system involves the heart and blood vessels; measured by blood pressure and heart rate.
Blood pressure: pressure exerted by blood inside the artery walls; it is responsive to a number of conditions
espeicially stress; expressed with 2 numbers: Systolic – larger number, referring to the maximum pressure within the system produced when the heart
Diastolic – smaller number; refers to the resting pressure inside the system between heart contractions
Heart rate: beats per minute (bpm); can be measured by measuring time interval between successive beats, if
each interval is only one second, then heart rate is 60 bpm; as heart rate is increasing, it indicates the body is
preparing for action; good indicator of stress/anxiety, cognitive effort.
Cardiac reactivity: increase in blood pressure and heart rate in times of stress; associated with people who are
Type A Personality (impatient, competitive, hostile); evidence suggests that chronic cardiac reactivity
contributes to coronary artery disease and heartattacks which may be why type A personality trait is
associated with a higher likelihood of heart disease and heart attacks.
Electroencephalogram (EEG): the brain produces small amounts of electricity which can be measured by
placing electrodes on the scalp; recordings can be obtained for various regions of the brain while the person is
asleep, relaxed or doing a task; interested in finding whether different regions of the brain show activity for
different people (introverts/extroverts).
Evoked potential technique: EEG is measured but participant is given a stimulant and the researcher assesses
the p’s brain.
Non-invasive techniques for mapping the structure and function of the brain - PET: Positron emission
tomography fMRI: functional magnetic resonance imaging; shows which portions of the brain are active while
a person is performing a certain task. Ex. High activity in control group, low in psychopath group, while looking
at violent images.
Neuroticism is correlated with increased frontal brain activation to negative images; Extraversion is correlated
with increased frontal brain activation to positive images.
Electrodermal sweat gland activity controlled by sympathetic nervous system anxiety, guilt, effort, pain noise, emotional
Cardiovascular blood pressure, heart rate controlled by autonomic nervous system fight or flight response, mental effort,
stress stress, social anxiety, effort
EEG Brain’s electrical activity alertness, brain activation resting with eyes closed, reading.
Evoked EEG electrical activity in response to stimuli attention, recognition brief sensory stimuli, emotional stimuli
Neuroimaging (fmri, pet) brain’s energy metabolism specific areas responsible for cognitive control, emotion, memory, pain
tasks that activate response systems.
Other measures: antibodies (immune system), testosterone (hormone system, steroid), cortisol (hormone system, adrenal),
serotonin, dopamine, MAO etc (neurotransmitters).
Physiological Personality Theories and Related Research/Clinical Findings
EYSENCK’S ORIGINAL THEORY
ARAS: ascending reticular activating system; structure in brain system thought to control overall cortical
arousal; those who are introverts are characterized by high levels of activity in the ARAS; ARAS was thought of
as a gateway. Introversion – higher resting cortical arousal (ARAS lets too much in, engage in quiet behaviour to keep their
heightened level in chech).
Extraversion – lower resting cortical arousal (ARAS lets too little in); they need to increase their level or
Those high in introversion or extraversion do not have different resting states of arousal, but are different
under certain levels of stimulation; the difference lies in the degree of arousability (arousal response);
introverts show enhanced physiological reactivity.
SENSITIVTY TO REWARD AND PUNISHMENT
Reinforcement sensitivity theory: based on brain function research with animals, a model of human
personality based on two hypothesized biological systems in the brain.
1) Behavioural activation system (BAS) – responsive to incentives (cues for reward) and regulates
approach behaviour; active BAS impulsivity
2) Behaviour Inhibition System (BIS) responsive to punishment, uncertainty and motivates
inhibition/avoidance; active BIS Anxiety
Impulsivity: high extraversion; moderate neuroticism; responds poorly to punishment & more to reward.
Anxiety: high neuroticism; moderate introversion.
- Tendency to seek out thrilling and exciting activities, to take risks, and to avoid boredom.
Sensory deprivation: having no sensory stimulants; ex. Dark room experiment.
Optimal level of arousal: people are motivated to reach their optimal level of arousal; if they are
underaroused an increase is rewarding; if they are over aroused, a decrease is rewarding; we are motivated to
seek out tension and stimulation, the nervous system needs some sensory input.
Physiological Basis of Sensation Seeking