Cognitive Connie
Understanding physiological approaches to personality
Physiological approaches seek to explain personality differences in terms of underlying biological systems — the reticular activating system, limbic reactivity, neurotransmitter balance, and circadian rhythms. The core hypothesis is that the stable individual differences we call personality reflect stable individual differences in these physiological systems.
Key figures
Hans Eysenck
1916–1997Developed the arousal theory of extraversion, proposing that the ARAS mediates cortical arousal differences between introverts and extroverts, and grounding personality theory in neurophysiology.
Marvin Zuckerman
1928–2018Developed the sensation seeking construct and linked it to biological substrates including MAO activity and dopaminergic function. His biosocial theory of personality integrated trait measurement with neurobiological research.
Jeffrey Gray
1934–2004Developed the Behavioural Inhibition System / Behavioural Activation System model and Reinforcement Sensitivity Theory, providing a neuropsychological framework for understanding anxiety and impulsivity as personality dimensions. His Neuropsychology of Anxiety (1982, revised 2000) is a foundational text.
Robert Cloninger
1944–presentPsychiatrist who proposed the tridimensional personality model linking temperament dimensions to specific neurotransmitter systems. Developed the Tridimensional Personality Questionnaire (TPQ) and later the Temperament and Character Inventory (TCI).
Key concepts
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.
Test your knowledge
Sources
Last reviewed July 2025- 1.
Eysenck H.J. (1967). The Biological Basis of Personality. Charles C. Thomas.
+About this source
Foundational text linking personality dimensions to biological mechanisms of cortical arousal.
- 2.
Zuckerman M. (1994). Behavioral Expressions and Biosocial Bases of Sensation Seeking. Cambridge University Press.
+About this source
Comprehensive account of sensation seeking as a biologically grounded personality dimension with neurochemical correlates.