According to Eysenck's arousal theory of extraversion, how do introverts and extroverts differ in baseline cortical arousal, and what behavioural consequence follows?

A: Extroverts have higher baseline cortical arousal and therefore seek more stimulation to reduce discomfort; introverts have lower arousal and are happy with minimal input

B: Introverts have higher baseline cortical arousal — they are closer to their optimal level at rest and therefore prefer less additional stimulation; extroverts have lower baseline arousal and seek stimulation to raise it towards the optimum

C: Introversion and extraversion differ only in limbic system reactivity, not cortical arousal

D: Cortical arousal is equivalent in introverts and extroverts; they differ only in their subjective threshold for social stimulation

Correct: Introverts have higher baseline cortical arousal — they are closer to their optimal level at rest and therefore prefer less additional stimulation; extroverts have lower baseline arousal and seek stimulation to raise it towards the optimum

Eysenck proposed that introverts have chronically higher baseline cortical arousal (via the ascending reticular activating system, ARAS) and are therefore closer to or at their optimal arousal level even at rest. Additional social stimulation is more aversive for introverts because it overshoots the optimum. Extroverts, chronically underaroused at baseline, seek out stimulating environments to raise their arousal to the optimal level. This generates specific predictions: introverts should be more easily conditioned (more reactive), prefer quieter environments, and perform better on tasks requiring sustained concentration.

True or False: Eysenck predicted that introverts would be more easily classically conditioned than extroverts because of their higher baseline cortical arousal.

Answer: True

Higher cortical arousal in introverts should make them more reactive to stimuli and therefore more easily conditioned. Eysenck reviewed evidence that introverts acquired conditioned responses more rapidly and extinguished them more slowly than extroverts. This prediction connects to Eysenck's broader theory linking extraversion to differences in socialisation: introverts, being more easily conditioned, should more readily internalise social norms, which may partly explain their more inhibited social behaviour. The evidence supporting this prediction is mixed and the specific ARAS mechanism has been questioned.

Jeffrey Gray's Reinforcement Sensitivity Theory proposes two major motivational systems. What does the Behavioural Inhibition System (BIS) respond to and what does it produce?

A: BIS responds to reward signals and produces approach motivation, increased energy, and positive affect

B: BIS responds to signals of punishment, non-reward, novelty, and innate fear stimuli; it produces inhibition of ongoing behaviour, increased arousal and attention, and negative affect — serving to protect the organism from threat

C: BIS responds to social stimuli specifically and produces social anxiety and withdrawal

D: BIS monitors for homeostatic imbalance and produces autonomic arousal to restore equilibrium

Correct: BIS responds to signals of punishment, non-reward, novelty, and innate fear stimuli; it produces inhibition of ongoing behaviour, increased arousal and attention, and negative affect — serving to protect the organism from threat

In Gray's Reinforcement Sensitivity Theory, the BIS is activated by signals of potential punishment, non-reward, novelty, and innate fear stimuli (e.g., pain, predators). BIS activation produces behavioural inhibition — stopping ongoing behaviour — along with increased attention, vigilance, and negative affect. It functions as a "check and evaluate" system that pauses ongoing activity to assess potential threats. High BIS sensitivity is associated with anxiety, neuroticism, and behavioural inhibition in response to uncertainty.

What does the Behavioural Activation System (BAS) respond to, and what personality trait does high BAS sensitivity predict?

A: BAS responds to punishment signals and predicts trait neuroticism

B: BAS responds to conditioned signals of reward, non-punishment, escape from punishment, and novelty; high BAS sensitivity predicts impulsivity, reward-seeking, extraversion, and approach motivation

C: BAS responds to social threat signals and predicts trait agreeableness

D: BAS is identical to the dopamine reward system and predicts addiction vulnerability exclusively

Correct: BAS responds to conditioned signals of reward, non-punishment, escape from punishment, and novelty; high BAS sensitivity predicts impulsivity, reward-seeking, extraversion, and approach motivation

The BAS (also called the Behavioural Approach System or reward system) is activated by conditioned stimuli associated with reward, relief from punishment, or novelty that may signal reward. It produces positive affect, motivates approach behaviour, and increases energy directed toward goals. Gray linked high BAS sensitivity to impulsivity and reward sensitivity, and it maps onto the extraversion/positive emotionality pole. Contemporary neuroscience has identified dopaminergic pathways as central to BAS function, consistent with findings linking dopamine to novelty-seeking and reward motivation.

Which neurotransmitter system is most prominently associated with Gray's BIS and trait anxiety?

A: Dopamine

B: Serotonin (and noradrenaline), particularly in the septo-hippocampal system

C: Acetylcholine

D: GABA

Correct: Serotonin (and noradrenaline), particularly in the septo-hippocampal system

Gray identified the septo-hippocampal system (SHS) as the neural substrate of the BIS. Serotonin and noradrenaline are the primary neurotransmitters involved. Anxiolytic drugs (benzodiazepines, SSRIs, barbiturates) reduce BIS reactivity, consistent with their action on serotonergic and GABAergic systems. Cloninger's tridimensional model similarly proposed that harm avoidance — closely related to BIS sensitivity — is mediated by serotonergic tone. High serotonin activity is associated with behavioural inhibition and risk aversion.

Cloninger's tridimensional personality model proposed three temperament dimensions directly linked to specific neurotransmitter systems. Which pairing is correct?

A: Harm Avoidance ↔ dopamine; Reward Dependence ↔ serotonin; Novelty Seeking ↔ noradrenaline

B: Novelty Seeking ↔ dopamine (low); Harm Avoidance ↔ serotonin (high); Reward Dependence ↔ noradrenaline (low)

C: Novelty Seeking ↔ serotonin; Harm Avoidance ↔ dopamine; Reward Dependence ↔ endorphins

D: All three dimensions are mediated by dopamine across different receptor subtypes

Correct: Novelty Seeking ↔ dopamine (low); Harm Avoidance ↔ serotonin (high); Reward Dependence ↔ noradrenaline (low)

Cloninger's (1987) tridimensional model proposed that three heritable temperament dimensions each reflect the activity of a specific monoamine system: Novelty Seeking (impulsive, exploratory, quick-tempered) is mediated by low dopaminergic activity; Harm Avoidance (anxious, inhibited, pessimistic) is mediated by high serotonergic activity; Reward Dependence (sentimental, socially sensitive, persistent) is mediated by low noradrenergic activity. Subsequent molecular genetic and pharmacological research has not fully supported these specific mappings, but the model was influential in linking personality to neurobiology.

Zuckerman's "sensation seeking" trait has been linked to which neurobiological substrate?

A: High serotonin and low noradrenaline activity

B: Low monoamine oxidase (MAO) activity, dopaminergic reward sensitivity, and testosterone

C: High cortisol reactivity and hypothalamic-pituitary-adrenal axis sensitivity

D: Overactivity of the septo-hippocampal system and GABAergic inhibition

Correct: Low monoamine oxidase (MAO) activity, dopaminergic reward sensitivity, and testosterone

Zuckerman proposed that sensation seeking — the need for varied, novel, and complex sensations and the willingness to take risks to obtain them — is linked to low monoamine oxidase (MAO) activity (MAO breaks down dopamine, serotonin, and noradrenaline, so low MAO = more monoaminergic activity), high dopaminergic reward sensitivity (making novel stimuli more reinforcing), and testosterone (linked to risk tolerance and dominance behaviour). High sensation seekers show blunted cortisol responses to novel stimuli, consistent with their lower aversion to novelty.

Research on chronotypes (morning and evening types) has found which associations with Big Five personality traits?

A: Morning types score higher on Neuroticism and Openness; evening types score higher on Conscientiousness

B: Morning types tend to score higher on Conscientiousness and Agreeableness; evening types tend to score higher on Openness to Experience and Extraversion, and somewhat higher on Neuroticism

C: Chronotype is unrelated to personality; the association is entirely explained by age and gender

D: Evening types score higher on all Big Five traits except Neuroticism

Correct: Morning types tend to score higher on Conscientiousness and Agreeableness; evening types tend to score higher on Openness to Experience and Extraversion, and somewhat higher on Neuroticism

Several studies have found consistent personality-chronotype associations. Morning types (larks) tend to score higher on Conscientiousness — consistent with their scheduled, disciplined approach to time — and Agreeableness. Evening types (owls) tend to score higher on Openness to Experience, which aligns with their preference for novel experiences, unconventional schedules, and creative pursuits. Evening types also score somewhat higher on Neuroticism in some samples. These associations may reflect shared biological underpinnings: circadian rhythms interact with the arousal systems linked to Eysenck's dimensions.

True or False: Chronotype (morning vs. evening preference) has a significant heritable component, with twin studies estimating heritability at approximately 50%.

Answer: True

Twin and molecular genetic studies have established that chronotype is substantially heritable. Koskenvuo et al. (2007) found heritability estimates of approximately 54% for eveningness in a large Finnish twin sample. Genome-wide association studies (GWAS) have identified multiple genetic variants associated with chronotype, including variants in circadian clock genes (PER2, CRY1). This heritable basis helps explain why chronotype shows consistent personality associations — both may share genetic underpinnings via shared biological mechanisms regulating arousal and rhythm.

What does research on the "optimal level of arousal" framework predict about performance and personality?

A: Performance improves linearly with arousal level, so extroverts always outperform introverts on all tasks

B: There is an inverted U-shaped relationship between arousal and performance (Yerkes-Dodson law); introverts, having higher baseline arousal, perform better at lower stimulation levels, while extroverts perform better at higher stimulation levels

C: Arousal has no relationship to cognitive performance, only to emotional experience

D: Optimal arousal level is identical for all individuals and varies only with task difficulty, not personality

Correct: There is an inverted U-shaped relationship between arousal and performance (Yerkes-Dodson law); introverts, having higher baseline arousal, perform better at lower stimulation levels, while extroverts perform better at higher stimulation levels

The Yerkes-Dodson (1908) law established an inverted-U relationship between arousal and performance — too little arousal leads to poor performance through inattention; too much leads to poor performance through interference. Eysenck applied this to personality: because introverts have higher baseline arousal, they reach optimal performance at lower environmental stimulation levels, while extroverts need more stimulation to reach peak performance. This predicts that introverts benefit from quiet study environments while extroverts may benefit from mild background stimulation — predictions that have received mixed empirical support.