RT Journal Article SR Electronic T1 The Pupillary Light Response Reflects Visual Working Memory Content JF bioRxiv FD Cold Spring Harbor Laboratory SP 477562 DO 10.1101/477562 A1 Hustá, Cecília A1 Dalmaijer, Edwin A1 Belopolsky, Artem A1 Mathôt, Sebastiaan YR 2018 UL http://biorxiv.org/content/early/2018/11/27/477562.abstract AB Recent studies have shown that the pupillary light response (PLR) is modulated by higher cognitive functions, presumably through activity in visual sensory brain areas. Here we use the PLR to test the involvement of sensory areas in visual working memory (VWM). In two experiments, participants memorized either bright or dark stimuli. We found that pupils were smaller when a pre-stimulus cue indicated that a bright stimulus should be memorized; this reflects a covert shift of attention during encoding of items into VWM. Crucially, we obtained the same result with a post-stimulus cue, which shows that internal shifts of attention within VWM affect pupil size as well. Strikingly, pupil size reflected VWM content only briefly. This suggests that a shift of attention within VWM momentarily activates an “active” memory representation, but that this representation quickly transforms into a “hidden” state that does not rely on sensory areas.