Stress, verbal cognitive activity and bilateral electrodermal responses

Area of Science:

• Psychophysiology
• Cognitive Neuroscience
• Human Electrophysiology

Background:

• Electrodermal activity (EDA), specifically skin potential responses (SPRs), is a key indicator of sympathetic nervous system arousal.
• The lateralization hypothesis suggests functional asymmetries between the brain's hemispheres, potentially reflected in peripheral physiological responses.
• Previous research has explored hemispheric differences in cognitive and emotional processing using EDA, but findings on lateralization remain debated.

Purpose of the Study:

• To investigate the degree of lateralization in bilateral electrodermal activity (skin potential responses) during distinct psychological conditions.
• To test the hypothesis of lateralization in SPRs during a verbal cognitive task versus a stressful situation.
• To compare the symmetry and lateralization of SPRs between the right and left hands across different task demands.

Main Methods:

• Simultaneous recording of electrodermal activity (skin potential responses) from both the right and left hands of 30 healthy, right-handed subjects.
• Utilized a reference electrode placed subdermally on the forearm for accurate signal detection.
• Subjects underwent two conditions: a verbal cognitive task (reflection phase) and a standardized stressful situation.

Main Results:

• A very high percentage of electrodermal activity (skin potential responses) exhibited equal amplitudes between the right and left hands in both tested conditions.
• Contrary to the lateralization hypothesis, SPRs were found to be significantly less lateralized during the stressful situation compared to the verbal cognitive task.
• The findings indicate a high degree of bilateral symmetry in electrodermal responses, challenging assumptions of pronounced lateralization in this measure.

Conclusions:

• Electrodermal responses (skin potential responses) demonstrate substantial bilateral symmetry, even during tasks expected to elicit lateralized processing.
• The degree of SPR lateralization is condition-dependent, being reduced under stressful conditions compared to cognitive tasks.
• These findings suggest that electrodermal activity may not strongly reflect hemispheric lateralization as hypothesized, particularly in response to stress.