Individual differences in physiological responses and type A behavior pattern.

The relationships between individual differences in psychophysiological responses and tendency of Type A behavior pattern (TABP) were investigated during mental arithmetic (MA) at a steady rhythm, challenging calculation (Uchida-Kraepelin serial addition test: UK test), music listening, and exposure to an 80 dB SPL of white noise. Each mental task was sustained for 5 minutes. Sixteen healthy Japanese adults, (10 males and 6 females) with an age from 18 to 36 years old volunteered for this study. The KG's Daily Life Questionnaire (KG Questionnaire) was used to investigate the tendency toward TABP, which included three sub-factors: aggression-hostility, hard-driving and time urgency, and speed-power items. Recorded physiological variables were respiratory rate (RR), skin resistance response (SRR), eyeblinks, and heart rate (HR) calculated using frequency analysis to render high frequency power (HF) and the ratio of low/high frequencies (L/H ratio). During the MA and UK tests, significant increases in HR, L/H ratio, RR occurred, while significant decreases in HF were observed. Eyeblinks significantly increased during the MA test and significantly decreased during the UK test. During music and white noise, no significant changes occurred except for SRR, which decreased significantly. The coefficient of variances in each response was over 20% for almost all variables, indicating that individual differences in the magnitude of each response were large, even if the direction (increase or decrease) of the change was the same in almost all subjects. The highest correlation coefficients (r) between the mean values of relative magnitude for each variable and TABP scores during the MA and UK tests were obtained for the L/H ratio (MA: r = 0.591, UK test: r = 0.577) and the RR (MA: r = -0.576, UK test: r = -0.511). These values were statistically significant (p < 0.05). Similar results were obtained for TABP sub-factors. Though other investigations have reported relationships between HF and TABP, we found no significant relationship. It was suggested that sympathetic nerve activity became greater for TABP individuals than for Type B individuals under stress conditions.