Physiological Approaches to Personality

All 9 Terms & Definitions

Ascending Reticular Activating System (ARAS)

The brainstem system responsible for regulating overall cortical arousal. Eysenck proposed that introverts have chronically higher ARAS-mediated cortical arousal, leading them to avoid additional stimulation, while extroverts have lower baseline arousal and seek stimulation.

Eysenck's arousal theory of extraversion

Introverts have higher baseline cortical arousal and are closer to their optimal level at rest. They prefer less stimulation. Extroverts have lower baseline arousal and seek stimulation to reach the optimum. Predicts differences in conditioning, environmental preferences, and performance under varying stimulation levels.

Optimal level of arousal (Yerkes-Dodson)

Performance follows an inverted-U function of arousal. Too little arousal = underperformance through inattention; too much = overperformance interference. Introverts reach optimal performance at lower stimulation levels than extroverts.

Behavioural Inhibition System (BIS)

Gray's threat-detection system, activated by signals of punishment, non-reward, novelty, and innate fear stimuli. BIS activation produces behavioural inhibition, increased vigilance, and negative affect. Septo-hippocampal system; mediated by serotonin and noradrenaline. High BIS sensitivity ↔ trait anxiety.

Behavioural Activation System (BAS)

Gray's reward-approach system, activated by conditioned signals of reward, relief from punishment, and novelty. Produces positive affect, approach motivation, and energised goal-directed behaviour. Mediated by dopaminergic pathways. High BAS sensitivity ↔ impulsivity, reward sensitivity, extraversion.

Reinforcement Sensitivity Theory (RST)

Gray's neuropsychological model of personality (updated 2000) proposing that individual differences in BIS and BAS sensitivity underlie trait anxiety and impulsivity/extraversion respectively. Later revisions distinguished BAS further and added a Fight-Flight-Freeze System (FFFS).

Cloninger's tridimensional model

Proposes three temperament dimensions each linked to a neurotransmitter system: Novelty Seeking ↔ dopamine; Harm Avoidance ↔ serotonin; Reward Dependence ↔ noradrenaline. Influential but not fully supported by molecular genetic evidence.

Sensation seeking (Zuckerman)

The need for varied, novel, and complex sensations and the willingness to take risks. Linked to low monoamine oxidase (MAO) activity, dopaminergic reward sensitivity, and testosterone. High sensation seekers show blunted cortisol responses to novel stimuli.

Chronotype

Individual differences in the timing of circadian rhythms — the preference for morning (lark) or evening (owl) activity. Substantially heritable (~50%). Morning types tend toward higher Conscientiousness and Agreeableness; evening types toward higher Openness and Neuroticism.