BIOLOGICAL BASIS of EXTROVERSION/INTROVERSION

• ARAS System

  • Ascending Reticular Activation System
  • Cortical Excitation and Inhibition
• High ARAS Arousal


  Predisposes to Introversion
• Low ARAS Arousal


  Predisposes to Extraversion
• Evidence: Introverts have higher sedation threshold from Extraverts
• EMPIRICAL FINDINGS of BIOLOGICAL BASIS OF EXTRAVERSION/INTROVERSION

  1. Introverts less tolerant of painful electric shock
  2. After high dose of caffeine: Introverts have poorer performance (overstimulated) and Extraverts have better performance (stimulated)
  3. Frontal Lobes of Introverts more active than Extraverts (PET Scan)