Effects of Open Versus Closed Eyes on Physiological Conditions During a Working Memory Task

Abstract

The purpose of this study was to investigate the effect of open versus closed eyes during a working memory task on physiological indices of workload. We used the NASA-TLX as a subjective evaluation, and electroencephalograms and oxygenated hemoglobin (oxyHb) concentrations measured via near-infrared spectroscopy as physiological indices of workload. Subjects performed n-back tasks while simultaneously performing an alpha attenuation test (eyes closed [30 s], eyes open [30 s] x 3) for 3 min. Increasing the task load increased the weighted workload and oxyHb. Since Fz / αPz in the open-eyes state shows the same trend as oxyHb, we were able to confirm that Fz / αPz in the open-eyes state is an index of the degree of the workload. However, Fz / αPz varied little between tasks or over time in the closed-eyes state. These results suggest that Fz / αPz is suitable as an index for indicating the degree of a workload only when the eyes are open.