PT  - JOURNAL ARTICLE
AU  - Hustá, Cecília
AU  - Dalmaijer, Edwin
AU  - Belopolsky, Artem
AU  - Mathôt, Sebastiaan
TI  - The Pupillary Light Response Reflects Visual Working Memory Content
AID  - 10.1101/477562
DP  - 2018 Jan 01
TA  - bioRxiv
PG  - 477562
4099  - http://biorxiv.org/content/early/2018/11/27/477562.short
4100  - http://biorxiv.org/content/early/2018/11/27/477562.full
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.