Effects of Cognitive Load and State of Vigilance on Sympathetic Skin Response

INTRODUCTION: The skin conductance response is one of the noninvasive peripheral markers of the activity of sympathetic nervous system. Skin conductivity level monitorization during cognitive performance processes is used as a physiological indicator of task-related alertness and attention. In this study, it is aimed to investigate the relationship between task related sympathetic activity and reaction time in students 18–22 years of age.
METHODS: A total of 20 healthy male and female student were included into the study. Hand preference and color blindness test were applied to the participants. Electrodermal activity recordings were recorded as tonic and phasic recording during all tasks. Different colored 2-dimesional geometric objects were presented in fixed and random intervals through the computer system. The task performance of pressing the predefined button as soon as the stimulus appeared on computer screen was investigated in relation with cognitive load and sympathetic stress response.
RESULTS: Applying an increased amount of cognitive load increases sympathetic stress response (p<0.001). An increase in reaction time was observed with increasing amount of cognitive load (p<0.05). The similar task levels, on the other hand, cause statistically higher mean skin conductivity levels when visual stimulus is presented at fixed interval rather than random stimulus interval.
DISCUSSION AND CONCLUSION: Beyond the expectations, our novel findings highlight the importance of internal timestamp processes of individuals. Therefore, we may suggest that time estimation processes play critical role in generation of sympathetic stress response when compared to vigilance state caused by simply waiting for random stimuli.