Abstract
In this study, we considered validity of pupuil size as an on-line measure of retention in visual working memory. Actually, Unsworth and Robinson (2015) measured pupil size during a change detection task and found that pupil size changes with the increase of number of items to be held in visual working memory. We conducted a replication attempt of Unsworth and Robinson (2015) and found the similar results (Exp 1). However, it is possible that the display brightness level or the encoding processing of the sample array might have influenced changes of the pupil size. To exclude these possibilities, we used a visual search task presenting the same array as the search array (Exp 2). In this condition, the pupil dilation did not persist during the delay period. The results indicated that pupil size is a valid on-line measure of retention in visual working memory.
