Effect of Age on Heart Rate Responses and Subjective Mental Workload During Mental Tasks

Abstract

We investigated the effect of age on heart rate (HR) responses and subjective mental workload during mental tasks. In this study, 55 male participants performed a mental arithmetic (MA) task and a mirror tracing (MT) task for 5 min each. Electrocardiogram (ECG) was recorded during these mental tasks and resting periods. Low frequency component (LF), high frequency component (HF), and LF/HF ratio of heart rate variability (HRV) were derived from ECG signals. NASA Task Load Index (NASA-TLX) was used to evaluate the subjective mental workload during each task. In the results, HR was significantly larger in the MA task than the resting period. LF was significantly smaller in the MA than the resting period before the task. On the other hand, no HR changes from the baseline in the MT task were found, suggesting that Pattern 2 response might appear. In the results of HRV indices, decrease in LF suggests the inhibition of the parasympathetic nervous system activity by the task. These results are consistent with those of our previous studies. No significant main interaction with age and blocks (MA, MT and resting periods) were found in physiological responses except for LF/HF and subjective mental workload score. Therefore, the physiological responses induced by mental tasks might be more susceptible to task characteristic than to aging. This study partly supported the previous study.