The Effect of Task Difficulty on the Steady State Visual Evoked Response

Abstract

Steady State Visual Evoked Responses to sum-of-sine wave modulated light were measured for subjects as they performed a decision making task. Describing function phase values demonstrated a positive shift under task conditions. For those subjects classified as Alpha producers (peak response in the 8 to 12 Hz region) there was an attenuation of gain with increasing task difficulty. In the beta range (above 12 Hz) a resistance to gain attenuation with increasing task difficulty, even to the point of gain increase, was observed.