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Chapter 7

PSYC 2740 Chapter Notes - Chapter 7: Extraversion And Introversion, Sertraline, Reward System

Course Code
PSYC 2740
Stephen Lewis

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Chapter 7: Physiological Approaches to Personality
Elliot personality was changed after he had small brain tumor removed from front of his head
- Increased impulsivity and lack of self-control can be caused by disruptions between frontal
lobes which are executive center of the brain
Phineas Gage foreman, iron rod went up through left check below cheekbone, through left
eye, and out top of skull changed his personality, became aggressive and impulsive,
disregarded social conventions etc.
Physiological characteristics (functioning of organ systems within the body)can be measured
mechanically and reliably
Physiological systems
- Nervous system (brain and nerves)
- Cardiac system (heart, arteries, veins)
- Musculoskeletal (muscles and bones that make all movement/behavior possible)
Differences in in physiological characteristics are related to differences in important personality
characteristics and behavior patterns
A Physiological Approach to Personality
Specific statements about what traits are connected to which physiological reactions under
which conditions or in response to which stimuli
Need to build theoretical bridge between personality dimension of interest and physiological
variables in order to use physiological concepts to help explain personality
Physiological Measures Commonly Used in Personality Research
Most obtained from electrodes sensors placed on surface of participants skin
Before had to be hooked up to machine but now use telemetry electrical sent to polygraph
through radio waves
3 physiological measures particular interest
1. Electrodermal activity (skin conductance of electricity)
- Sweat glands on feet and hands influenced by sympathetic nervous system part of the
autonomic nervous system that prepares body for action (fight or flight)
- When system is activated (anxiety, startle or anger)sweat glands fill with salt water, if
reaction is strong, sweat spills over creating sweaty palms before visible can be
detected with small amount of electricity
- Electrodermal activity or skin conductance is when water from glands conducts
- Place 2 electrodes on palm of one hand, low voltage of electricity put through one,
measure how much comes through at other difference tells how well skin is
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conducting electricity more sympathetic nervous system activity, the more water
produced, the better skin conducts electricity
- Electrodermal responses can be from a bunch of stimuli (ex. pain, emotion, sudden
noises etc.) phenomenon of interest is absence of external stimuli
- Anxiety, neuroticism associated with nonspecific electrodermal response sympathetic
nervous system in state of chronic activation
2. Cardiovascular measures
- Blood pressure = pressure exerted by blood on inside of artery walls, expressed in
diastolic and systolic pressure
- Systolic larger number, maximum pressure within cardiovascular system produced
when heart muscle contracts
- Diastolic smaller number, resting pressure inside system between heart contractions
- Blood pressure can increase in number ways heart may pump larger stroked
generating more volume or artery walls may narrow both happen through activation
of sympathetic nervous system during flight/fight response
- Heart rate (beats-per-minute/BPM) can measure time interval between beats (beat-by-
beat) if interval is exactly one second heart rate is 60 BPM
- As heart rate increases indicates person’s body is preparing for action –fight/flight
- Cardiac reactivity increase in blood pressure and heart rate during times of stress,
associated with type A personality (impatience, competitiveness, hostility) and may
contribute to coronary artery disease
3. Activity in the brain
- Electroencephalogram (EEG) brain spontaneously produces small amounts of
electricity, which can be measured by electrodes placed on the scalp can provide
useful information about patterns of activation in different regions of brain that may be
associated with different types of information processing tasks
- Evoked potential technique brain EEG is measured but participant given stimulus (tone
or flash of light) and response to stimulus is assessed
- Functional magnetic resonance imaging (fMRI) non-invasive imaging technique used to
identify specific areas of brain activity, as parts of brain are stimulated, oxygenated
blood rushes to activated area, resulting in increased iron concentrations in blood, it
detects these concentrations of iron and prints out colourful images indicating which
part of brain is used to perform tasks
- Personality correlated with degree of brain activation in response to positive and
negative images neuroticism correlated with increased frontal brain activation to
negative images, extraversion to positive images
Other Measures
Biochemical analysis of blood and saliva
- Ex. from saliva can tell how competent someone’s immune system is
- Immune system functioning may go up/down with stress or emotion
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