Chapter Seven Physiological Approaches to Personality
Chapter Seven Physiological Approaches to Personality
Why Study Physiology? Because, the brain is the origin of personality traits, and body functions that are controlled by the brain can be indicators of specific traits. Read the intro about Elliot, about the brain tumor, and about how the removal of just a little bit of brain matter altered this guy’s personality to the point of changing his whole life. This focus is an important bridge between theoretical psychological constructs and observable biological phenomenon.
Focus on the Nervous System
Observable Measures- necessary for scientific study, measures can be quantified
Quantitative Research- can be statistically/mathematically analyzed, which is necessary for the scientific method
Mind/Body Interconnectedness
Case Study- a springboard for further research (for Elliot- what part of the brain is associated with impulsivity, emotions; research into brain damage and personality changes, etc.) Notice, you will hear a lot about Phineas Gage, especially when it comes to serial killers and brain damage. He is simply a case study, and I don’t think he ever killed anyone. Can’t generalize.
Theoretical Bridge- talked about already.
Physiological Measures- what exactly are we measuring
Electrodes- sensors placed on the skin’s surface (not penetrating)
Polygraph- one example of use of electrodes, but is movement restrictive, only good for limited uses
Telemetry- new generation of electrodes that transmit the information gathered through radio waves.
Three Main Measures of Electrodes are
1. Electrodermal Activity- skin conductance of electricity
2. Cardiovascular Activity- heart and blood vessels
3. Brain Activity- brain activity
Electrodermal Activity- skin on your hands and feet contain high concentration of sweat glands which are influenced by the autonomic nervous system.
Autonomic Nervous System- body’s way of preparing you for action in times of danger. Involves the:
Sympathetic N.S.- the fight or flight response, also involved in states of anxiety, anger, surprise. Sweat glands fill with saltwater, prolonged SNS activity causes it to spill out (what we call sweating), which increases electrical conductivity (called electrodermal activity or skin conductance).
Parasympathetic N.S.- associated with returning your body to it’s normal functioning state. Important to regain activity associated with digestion, allows heart, lungs, sweat glands, etc. to rest. Impossible to have both in control at the same time, which is why so many therapists teach relaxation.
Electrodermal Activity- to measure this, the electrodes are placed on the palm of one hand and low voltage of electricity is passed from one electrode to the other via the skin. The more electricity measured in the second electrode, the greater the conductivity, the more sweat present. Increased in conductivity means increase in SNS activity. Person doesn’t feel this.
Skin Conductance-
Traits Measured- while this process can measure a great many things, the target reactions for personality would be things like guilt, anxiety, fear. Those individuals high in anxiety and neuroticism will more likely show higher levels of conductance even when they are instructed to relax, even before they are presented with any stimuli (questions, pictures of crime scenes). This suggests a SNS in chronic activation (which is not healthy, takes a great toll on the body).
Cardiovascular Activity
Blood Pressure- pressure exerted by blood on the vessel walls (low average is good, low can be dangerous, high obviously dangerous)
Diastolic/Systolic- systolic pressure (the larger number) measures the maximum pressure in the CV system produced when the heart muscle contracts (pushes the blood out). diastolic is the resting pressure between heart contractions. The harder the pressure, the harder your heart is working.
Heart Rate- measured in beats per minute. When body is preparing for action (SNS arousal), the heart rate increases. Heart rate naturally increases with cognitive effort, but rates of increase differ from person to person.
Cardiac Reactivity- people who show larger increases in heart rate when given difficult cognitive activities.
Traits Measured- cardiac reactivity has been associated with type A personalities (people who exhibit hostility, impatience, competitiveness). These folks are at increased risk of heart disease and heart attacks.
Brain Activity
EEG- by placing electrodes on the scalp, we can measure the electricity spontaneously produced by the brain. An electroencephalogram takes recordings from various regions of the brain in various states (asleep, relaxed, at a task), and can provide useful information about activity patterns in different situations.
Neuroimaging- looking at the brain, either the structure or at activity within it.
PET- positron emission tomography, uses radiation injected into the subject to measure blood flow to target organ (in this case, the brain). Downside- uses radiation.
MRI- uses magnetic field to observe the structure of the brain (or whatever you want to look at) in great detail.
fMRI- functional magnetic resonance imaging shows which portions of the brain are active during a specific activity, also measures blood flow, but without radiation.
Traits Measured- when subjects were shown negative and positive pictures during fMRIs, researchers noted specific brain changes associated with different emotions (depending on the picture). Personality differences emerged- neurotics showed more frontal lobe activity in response to the negative pictures, extraverts showed more frontal lobe activity to positive images. Cautions, doesn’t mean that it is hard-wired, just shows what is going on in the brain.
Other Measures
Saliva- spit contains body chemicals associated with specific processes or reactions, which correlate with certain personality traits.
Antibodies- immune system functioning may go up or down with levels of stress or emotions
Hormone Levels- testosterone has been linked to uninhibited, aggressive and risk taking behavior patterns
Cortisol- high levels indicate elevated stress reactions (higher levels in shy children).
Physiologically Based Theories
Eysenck- research was into physiological bases for personality traits (he had the supertraits).
Extraverson-Introversion- lets take the I-E test. Which one are you?
ARAS- Ascending Reticular Activating System (Located in the brainstem are an organization of nuclei and axon tracts known collectively as the reticular activating system) according to Eysenck, introverts have higher levels of activity here. Basically the ARAS controls overall cortical arousal, the theory being that introverts have a more “open” gateway between the nervous system and the cortex, the ARAS lets in too much stimulation, therefore they have a higher resting rate of cortical arousal than extraverts.
Arousal Levels
Baseline and Optimal Levels- Eysenck believed in an optimal level of arousal for any given task (you want to be more aroused for cognitive tasks than for a sleep state, but too much would interfere with that cognitive task). Since introverts have higher baselines naturally, they are usually above the optimum levels for more often that extroverts. Consider social situations, which stimulate physiological arousal in humans, where extraverts are relaxed, introverts are uncomfortable—overly aroused. Which is why they avoid these situations. Theoretically, at resting state, extraverts are below optimal levels, so they seek out stimulating activities to get to the optimal levels.
Evidence- to test this theory, EEGs were given to introverts and extraverts under various degrees of stimulation. Moderate levels of stimulation (and more) showed that the introverts’ arousal responses were larger and faster. Proof!
Arousability- studies also found that resting levels were not that different for introverts and extraverts, it was the response to stimulation where the differences were (Eysenck had to revise his theory). When performing more sedentary, calm tasks, since introverts are more easily aroused, they don’t become bored like extroverts do (why introverts are better at standard lecture-style learning, and extroverts learn better when there is more social interaction and hands-on activity). Now, take an introvert and extravert somewhere like a casino, and guess who wants to leave first. (Read other experiments).
Gray
Reinforcement Sensitivity Theory
BAS- Behavioral Activation System- response to incentives, like cues for reward, which regulates approach behavior. If the BAS recognizes something as potentially rewarding, it triggers “approach” behavior (example- children and icecream truck music).
BIS- Behavioral Inhibition System- response to punishment cues, frustration, and uncertainty. Brings about avoidance behaviors (example- you have been scolded for running out into the street). Think of the BAS as the accelerator, and the BIS as the brake.
Individual Differences- we have different sensitivities to the BIS and BAS, those that are sensitive to the BAS are more likely to be impulsive (sensitive to possibility of reward), and those sensitive to the BIS are more likely to be anxious, vulnerable to unpleasant emotions.
Anxiety and Impulsivity
Problems with this Theory-this has been presented as an alternative to Eysenck’s theory, but remember, neuroticism and introversion are, according to Eysenck, two separate traits. The important thing to think about is that if a person is not particularly sensitive to the BIS, then they are 1) more likely to be pleasure-seeking and impulsive, and 2) less likely to learn from punishment or be deterred by threat of punishment. Might be one reason criminals keep recommitting. Also, never let someone tell you the threat of the death penalty doesn’t work. It does, but not usually on those most likely to commit impulsive murders. Read 209 about gambling. Also, read 208 to find out if you are sensation-seeking.
Neurotransmitters and Personality
Zuckerman- believed there was a biological basis for sensation-seeking personalities, and it involved NTs. I don’t think I want to waste time describing what NTs are- most of you are psych majors and should know this by heart.
MAO’s- monoamine oxidase - some NTs are taken back up into the axon terminal after transmission, others hang around and wait to be broken down by special enzymes. If this action is inhibited, the NT would continue to link with the receptor, and neurotransmission would reoccur until the NT deteriorated or floated away. MAO is an enzyme that breaks down NTs. It is therefore and inhibitory agent itself, preventing overstimulation and overactivity of neurons. Low MAO levels are associated with low inhibition.
Cloninger’s Tridimensional Personality Model
Dopamine- novelty seeking based on low levels of dopamine (our natural reward system, which low levels of mean you have to get your pleasure from outside)
Serotonin- associated with harm avoidance (lower levels/activity are associated with anxiety, depression in mental illnesses—both of which are associated with avoidance behaviors, SSRIs are used to treat these disorders by raising levels of Serotonin in the synapse temporarily).
Norepinephrine- activates the SNS, but low levels are associated with low levels of arousal, so those individuals seek reward elsewhere.
Morningness-Eveningness- are you amorning person or an evening person? Do you like to sleep late, get up late, feel your peak in the late afternoon or evening? Do you bounce out of bed every morning, ready to go, ready to take on the world, but get to bed at a decent hour because you can’t keep your eyes open past 10pm? Guess what--this tends to be a stable characteristic. Take the quiz on 217.
Circadian Rhythms- fluctuations of body processes that involve the 24 hour day cycle (includes sleep, temperature, digestion).
Free Running- in studies of circadian rhythms, subjects are allowed to do whatever they want without time cues (clocks, light, sounds from nature). In isolation, circadian rhythms vary from 16 to 50 hours. What does this suggest? What is the strongest circadian rhythm cue?
Research- shows the average to be around 24 hours, but some have slightly shorter and others have slightly longer, which results in different peak times (shorter is earlier, meaning morning person).
Practical Applications- mismatches in these traits for one—say you, like me, are an evening person, and your husband is a morning person. The greater the difference, the lower the quality of the relationship. Less time spent together, more disruptive activities to those trying to sleep, get work done, etc. Also, look at schools. If you are a morning person, you should perform your cognitive tasks between 8 and 11am, if you are evening, between 5 and 11pm. Caffeine screws this up, or helps, depending on what you need. May be why it is the most used mind-altering substance in the world!! Think about when you should take classes, do homework. Seriously, though, we are somewhat adaptable at this. Also, since all the good TV shows come on at night, do your work earlier. Also, how much has artificial lighting influenced this?
Frontal Brain Asymmetry- not left-brained vs. right-brained (which is a crap theory, because research into IQ scores show high mathematical reasoning is correlated with high verbal reasoning, and creativity is correlated with intelligence). Refers to activity in the front parts of the left and right hemispheres, specifically alpha waves, which is associated with calm, relaxation, inattentiveness, sleepiness (more alpha waves). Left front part of brain is more active when experiencing pleasurable emotions, right front part when experiencing unpleasant emotions.
Research- suggests that more activity in one hemisphere over the other would put someone at risk of vulnerability to either unpleasant or pleasant states (leading to either avoidance or approach behaviors).
Implications- which movies you like might be a function of your brain asymmetry? Do you like scary films, or feel-good movies? Individuals with greater right-side activation would show more negative reactions to fear and disgust films, while left-activated individuals have more positive responses to happy or amusing films. Other studies show right-activated persons have higher levels of cortisol, a hormone associated with stress reactions. (Remember cortisol levels associated with calming influence of mothers.) Left frontal arousal associated with people with more positive dispositions (approach motivations). Persons with right frontal arousal may have lower threshold for responding to negative events, resulting in more strong negative emotional responses (avoid motivations).
Anger-Another study decided to try to disconnect the motivation-affect to figure out which variable was more influential, motivation OR affect. Using anger, which is an approach motivation with negative affect. The study showed left frontal arousal—suggesting the asymmetry reflects motivation directionality.
Tibetan Monk Study- looked at one monk with most left-sided asymmetry ever recorded (extremely low stress). Since mindfulness and relaxation are taught, this suggests that this asymmetry can be achieved with effort. One study took right-activated persons through an 8 week mindfulness/meditation training program, and the results were a significant shift toward left-activation. Also, immune systems were boosted (measured by amount of antibodies). Take that, Xanax.
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