The Biology of Personality Traits

EEG

Electrical activity in the brain recorded through the scalp. Good at measuring when activity happens but not where.

fMRI

Estimates activity in the brain through blood-oxygen changes. Good at measuring where activity occurs.

The dopaminergic system

Nucleus accumbens, Amygdala, Prefrontal cortex

Nucleus accumbens involved in

Reward processing; linked to Extraversion

Amygdala involve in

Responding to emotionally relevant stimuli.

Prefrontal cortex involved in

Higher-level processes such as decision-making and other cognitive functions.

Reward-value neurons

Respond to whether an outcome is better or worse than expected. This system appears linked to Extraversion.

Dopamine nueron: Salience or novelty-related neurons

Respond to relevant, new information, whether it is better or worse than expected. This system may be linked to Openness/Intellect.

Ascending reticular activating system (ARAS)

Helps regulate overall brain arousal, wakefulness, and alertness.

Genes and the environment influence on personality

Both influence the brain, which generates patterns of behavior+experience that we describe as personality

Personality neuroscience

The study of how personality traits relate to the brain

Hans Eysneck

Early major figure in personality nueroscience. Focused on ARAS.

Eysenck's original theory of Extraversion

Extraverts have lower baseline cortical arousal than introverts, so they seek more stimulation.

Eysenck's revised theory of extraversion

Introverts may be more easily aroused and become overstimulated with less stimulation.

Synapse

Space between neurons across which neurotransmitters travel

Gray's explanation of Extraversion

Extraversion is related to the Behavioral Activation System (BAS), dopamine, and sensitivity to rewards.

Main difference between Eysenck's original theory and Gray's theory

Eysenck focused on baseline cortical arousal; Gray focused on reward sensitivity, the BAS, and dopamine.

Three types of evidence support the dopamine theory of Extraversion?

Dopamine-related drug studies, EEG responses to reward feedback, and fMRI activity during reward anticipation.