Biological basis of personality

• How much of personality does Eysenck believe is genetic?

  • 67% of variance in personality traits is due to genetics
• How is extraversion linked to brain arousal?

  • extroverts have low cortical arousal and seek external stimulation

  • introverts have high cortical arousal and avoid stimulation
• How is neuroticism linked to the nervous system?

  • neurotics have an overactive sympathetic nervous system, making them more reactive to threats

  • stable individuals have a less reactive nervous system, making them calmer
• How is psychoticism linked to biology?

  • higher levels of testosterone are associated with higher psychoticism, explaining why men are more likely to score high on this trait