9 PHYSIOLOGY & PERSONALITY

Excitatory mechanisms

alert, awake, aroused

Inhibitory mechanisms

sleepy, drowsy, sluggish

Ascending Reticular Activating System (ARAS)

Maintains the balance between excitatory and inhibitory activity

If ARAS gateway is typically somewhat closed

Relatively low baseline level of cortical arousal

–   Extraverts’ situation

If ARAS gateway is typically open wide

Relatively high baseline level of cortical arousal

–   Introverts’ situation

Behavioural Activation System (BAS)

–       Responsive to rewards and regulates approach behaviour

–       Activity produces impulsivity

–       Neurotransmitter = dopamine

Based in the limbic System, In particular, the septal nuclei

& nucleus accumbens

Behavioural Inhibition System (BIS)

–       Responsive to punishment, frustration, uncertainty, and motivates ceasing, inhibiting, or avoidance behaviour.

–       Activity produces anxiety

–       Neurotransmitter = serotonin

Based in hippocampus and amygdala

Gray & McNaughton Sensitivity Theory

■ BAS: Reward sensitivity (similar to Extraversion)

–       Motivation to approach potential rewards, impulsivity

■ BIS: Conflict sensitive (similar to Neuroticism, Anxiety)

–       Motivation to avoid punishment, frustration, decisions

–       Sensitive to uncertainty, choice dilemmas, novelty

–       No longer focus on punishment—more internal conflict

■ FFFS (Fight, Flight, Freeze System): sensitive to danger

–       Demands immediate response

–       Response to punishment or threat

–       Panic, Fear

Sensation Seeking

Tendency to seek out thrilling, exciting activities, take risks, avoid boredom.

Monoamine Oxidase (MAO)

Enzyme that maintains neurotransmitter levels and sets the brakes in the nervous system.

High sensation seekers have low levels

Dopamine

Associated with pleasure

Related to Extraversion, and Openness in salience of information

Serotonin

Low levels associated with depression and anxiety

Related to Neuroticism

Positive Affectivity

A tendency to experience more positive emotions (joy, vigor, alert, excited)

Negative Affectivity

A tendency to experience more negative emotions (afraid, anxious, irritable, distressed)