Personality and PhysiologyPersonality and Physiology

What is the relationship What is the relationship between personality and our between personality and our

physiology?physiology?

It appears to be a complex It appears to be a complex interaction between the brain, interaction between the brain,

our bodies, and the our bodies, and the environment.environment.

The case of Phineas GageThe case of Phineas Gage

Frontal Lobes help to inhibit the Frontal Lobes help to inhibit the limbic system and appear to be limbic system and appear to be implicated in what we call our implicated in what we call our “personality.”“personality.”

Galen & Hippocrates – Fluid Theory Galen & Hippocrates – Fluid Theory (phlegm, blood, yellow bile, & black (phlegm, blood, yellow bile, & black bile)bile)

Early Greek philosophers had a Early Greek philosophers had a profound impact on important profound impact on important western philosophers such as western philosophers such as Immanuel Kant and Wilhelm Wundt. Immanuel Kant and Wilhelm Wundt.

Physiological systems are relatively Physiological systems are relatively easy to measure and appear to be easy to measure and appear to be associated with some personality associated with some personality characteristicscharacteristics

Sheldon’s Physiological Approach to Sheldon’s Physiological Approach to Personality (1940)Personality (1940)Ectomorph – skinny (thoughtful and Ectomorph – skinny (thoughtful and introverted)introverted)Mesomorph – muscular (assertive and Mesomorph – muscular (assertive and bold)bold)Endomorph – fat (sociable and fun Endomorph – fat (sociable and fun loving)loving)Research had significant bias issues!Research had significant bias issues!The most significant issue in this area of The most significant issue in this area of research is building a theoretical bridge research is building a theoretical bridge between physiology and personality.between physiology and personality.

There are different types of There are different types of physiological parameters.physiological parameters.

Most use surface Most use surface electrodes electrodes to to detect activitydetect activity

Some use Some use telemetrytelemetry to transmit this to transmit this activityactivity

The The autonomic nervous systemautonomic nervous system– Electrodermal activity/skin conductivityElectrodermal activity/skin conductivity– Appears to be a relationship between Appears to be a relationship between

skin conductivity and skin conductivity and neuroticism/anxietyneuroticism/anxiety

– Heart rate/blood pressureHeart rate/blood pressureInconvenience of measurementInconvenience of measurement

Type A PersonalityType A Personality (impatient, (impatient, competitive, & hostile)competitive, & hostile)

– Brain activityBrain activityEEG, evoked potentialEEG, evoked potential

fMRI (2003)fMRI (2003)

PET scansPET scans

– EMGEMGRelationship between muscle activity and Relationship between muscle activity and personalitypersonality

– Hormones (often measured by saliva Hormones (often measured by saliva analysis)analysis)

TestosteroneTestosterone

Cortisol (byproduct of adrenaline)Cortisol (byproduct of adrenaline)

MAO (thrill seeking)MAO (thrill seeking)

Physiologically based dimensions of Physiologically based dimensions of PersonalityPersonality

Extraversion – IntroversionExtraversion – Introversion– Optimal level of arousalOptimal level of arousal– Are there basic differences?Are there basic differences?

There are differences in arousabilityThere are differences in arousability

I > E in terms of arousabilityI > E in terms of arousability

E > I in terms of need for a stimulating E > I in terms of need for a stimulating environmentenvironment

– E will seek out stimulation for themselvesE will seek out stimulation for themselves

E = I in the level of stimulation if given the E = I in the level of stimulation if given the

opportunity to choose stimulationopportunity to choose stimulation

Sensitivity to Reward/PunishmentSensitivity to Reward/Punishment– Behavior Activating SystemBehavior Activating System (BAS) – is responsive (BAS) – is responsive

to incentives like cues for rewards and regulates to incentives like cues for rewards and regulates approachapproach behavior. They are vulnerable to behavior. They are vulnerable to unpleasant emotions including anxiety, fear and unpleasant emotions including anxiety, fear and sadness. BIS is responsible for the personality sadness. BIS is responsible for the personality dimension of dimension of anxiety.anxiety.

– Behavior Inhibiting SystemBehavior Inhibiting System (BIS) – is responsive (BIS) – is responsive to cues for punishment, frustration and to cues for punishment, frustration and uncertainty. It increases inhibitory behavior or uncertainty. It increases inhibitory behavior or brings about brings about avoidanceavoidance. They are vulnerable to . They are vulnerable to positive emotions and the ability of individuals positive emotions and the ability of individuals with a reactive BAS to inhibit behavior decreases with a reactive BAS to inhibit behavior decreases as he approaches a goal. BAS is responsible for as he approaches a goal. BAS is responsible for the personality dimension of the personality dimension of impulsivityimpulsivity, the , the inability to inhibit responses.inability to inhibit responses.

– Persons who are a bit introverted and Persons who are a bit introverted and highly neurotic are most prone to highly neurotic are most prone to anxiety while persons at the other end anxiety while persons at the other end of this continuum are seen as of this continuum are seen as extraverted and emotionally stable.extraverted and emotionally stable.

– Persons who are highly extraverted and Persons who are highly extraverted and a bit neurotic are seen as the most a bit neurotic are seen as the most impulsive while people at the other end impulsive while people at the other end of this continuum are introverted and of this continuum are introverted and emotionally stable.emotionally stable.

Persons with highly susceptible BIS tend Persons with highly susceptible BIS tend to have anxiety attacks, fears, worry, to have anxiety attacks, fears, worry, depression, phobias, obsessions, and depression, phobias, obsessions, and compulsion.compulsion.Persons with highly susceptible BAS Persons with highly susceptible BAS seek out interactions with others and seek out interactions with others and more susceptible to positive emotions.more susceptible to positive emotions.

– Highly BAS individuals appear to work Highly BAS individuals appear to work faster and are more accurate when faster and are more accurate when rewards are used while BIS individuals rewards are used while BIS individuals appear to work faster and improve appear to work faster and improve performance under punishment performance under punishment conditions.conditions.

Sensation SeekingSensation Seeking– The tendency to seek out thrilling and exciting The tendency to seek out thrilling and exciting

activities, to take risks, and avoid boredom.activities, to take risks, and avoid boredom.– The study of The study of sensory deprivationsensory deprivation reveals individual reveals individual

differences related to personality characteristics.differences related to personality characteristics.Most appear motivated to acquire any sensory input, Most appear motivated to acquire any sensory input, even if ordinarily such an input would be perceived as even if ordinarily such an input would be perceived as boring.boring.

Hebb’s Hebb’s Theory of Optimal Level of ArousalTheory of Optimal Level of Arousal suggests that people are motivated to reach suggests that people are motivated to reach an optimal level of arousal. If they are an optimal level of arousal. If they are underaroused, relative to this level, an underaroused, relative to this level, an increase in arousal is rewarding; conversely, increase in arousal is rewarding; conversely, if they are overaroused, a decrease in arousal if they are overaroused, a decrease in arousal is rewarding.is rewarding.

Zuckerman identified Zuckerman identified sensation seekerssensation seekers as as individuals who require a lot of stimulation individuals who require a lot of stimulation to reach their optimal level of arousal, are to reach their optimal level of arousal, are the least tolerant of sensory deprivation, the least tolerant of sensory deprivation, and find sensory deprivation to be and find sensory deprivation to be particularly unpleasant.particularly unpleasant.– Low sensation seekers were able to tolerate Low sensation seekers were able to tolerate

sensory deprivation better and for longer periods sensory deprivation better and for longer periods of time.of time.

– High sensation seekers have a need for high High sensation seekers have a need for high levels of stimulation in their daily lives.levels of stimulation in their daily lives.

– There appears to be a relationship between There appears to be a relationship between sensation seeking and the individual’s sensation seeking and the individual’s neurotransmitters.neurotransmitters.

Neurotransmitters and PersonalityNeurotransmitters and Personality– Monoamine Oxidase (degrades Monoamine Oxidase (degrades

neurotransmitters)neurotransmitters)Too much MAO and the individual has too Too much MAO and the individual has too little NT and nervous transmissions would little NT and nervous transmissions would diminish (lethargic). Low sensation seekers diminish (lethargic). Low sensation seekers & too much inhibition.& too much inhibition.

Too little MAO and the individual has too Too little MAO and the individual has too much NT and nervous transmissions would much NT and nervous transmissions would increase (shaky). High sensation seekers & increase (shaky). High sensation seekers & too little inhibition.too little inhibition.

What about the other What about the other neurotransmitters?neurotransmitters?– Dopamine Dopamine (associated with pleasure, (associated with pleasure,

functions in the reward system, and is functions in the reward system, and is called the “feel good” chemical)called the “feel good” chemical)

– SerotoninSerotonin (associated with depression, (associated with depression, anxiety, & irritability) (SSRI’s allow anxiety, & irritability) (SSRI’s allow serotonin to stay in synapse longer serotonin to stay in synapse longer allowing individuals to feel less depressed, allowing individuals to feel less depressed, even in non-depressed individuals)even in non-depressed individuals)

– NorepinephrineNorepinephrine (associated with (associated with activation of the autonomic nervous activation of the autonomic nervous system and the fight or flight response)system and the fight or flight response)

– Tridimensional Personality ModelTridimensional Personality Model is a is a model that suggests that there is a complex model that suggests that there is a complex interplay of these neurotransmitters.interplay of these neurotransmitters.

Novelty seeking – dopamineNovelty seeking – dopamine

Harm avoidance – serotoninHarm avoidance – serotonin

Reward dependence – norepinephrineReward dependence – norepinephrine

A good example of the complex A good example of the complex interplay of neurotransmitters is interplay of neurotransmitters is alcoholismalcoholism..– Some drink to seek novelty, some for Some drink to seek novelty, some for

pleasure boosting, some to relieve stress, pleasure boosting, some to relieve stress, some for harm avoidance, some for relief, some for harm avoidance, some for relief, and some because it is rewarding.and some because it is rewarding.

All of the approaches with regard to genes and All of the approaches with regard to genes and personality have common underlying basis in the personality have common underlying basis in the biology of the nervous system.biology of the nervous system.Morningness and eveningnessMorningness and eveningness– Tends to be stable over a lifetimeTends to be stable over a lifetime– Is based on an individuals circadian rhythmsIs based on an individuals circadian rhythms– While it is stable there is a gradual shift towards While it is stable there is a gradual shift towards

MorningnessMorningnessAffects who can live togetherAffects who can live togetherCognitive performanceCognitive performancePreferencesPreferences

Brain asymmetry and affective styleBrain asymmetry and affective style– Studies suggest that the left hemisphere is more active Studies suggest that the left hemisphere is more active

than the right when an individual is experience unpleasant than the right when an individual is experience unpleasant emotions and visa versaemotions and visa versa

– May reflect an underlying biological disposition or traitMay reflect an underlying biological disposition or trait– May also be related to the release of hormones like May also be related to the release of hormones like

Cortisol.Cortisol.