Cardiovascular measures are an important component of ANS function changes. Deceleration of the phasic heart rate is the cardiac depiction of orienting responses whereas phasic acceleration is the cardiac representation of the defensive responses. Studies examining difference between introverts and extraverts in terms of cardiovascular measures did not find any variation in the baseline or tonic heart rate. However, in vigilance conditions introverts show higher heart rate as compared to extraverts. Researchers studying sensation seeking behaviour have found heart rate deceleration when moderately intense novel stimuli are presented to high sensation seekers. The low sensation seekers display acceleration of heart rate.

The relationship between personality and electrical activities of the brain has also been studied. The introverts and extroverts have been found to be different with respect to alpha recording from the posterior regions of the skull. The amplitude and frequency of the alpha waves indicate the level of cortical activation. High arousal level is represented by low amplitude and high frequency ranging between 8-13 Hz.

Although the usage of imaging technique in personality studies is not new, there are still not many studies in this domain. Mathew et al. (1984) administered Eysenck Personality Inventory (Eysenck & Eysenck 1964) on 51 normal female volunteers and used the xenon inhalation technique to correlate regional blood flow with personality dimensions. They found inverse correlations between blood flow and extraversion. The correlation between blood flow and neuroticism was not significant. The findings suggest inverse relationship between extraversion and general cortical arousal. Couples of studies have correlated PET-glucose metabolic rate (GMR) and scores of Eysenck Personality Questionnaire. The findings show positive correlation between extraversion and GMR in frontal and temporal areas of the brain. Caudate and putamen areas were also correlated with extraversion.