Johan Hulleman¹, Aoqi Li¹, Jeremy M. Wolfe^2,3; ¹University of Manchester, ²Brigham and Women's Hospital, ³Harvard Medical School

In two eye tracking experiments, 20 participants searched for T amongst L’s on a 1/f^1.3 noise background (target prevalence 50%). The contrast of an item was defined as the difference between its grayscale [0-255] and average local background grayscale [75-180]. Absolute target contrast was 15, 45, 75, 105 in Experiment 1 and 15, 45, 75 in Experiment 2. Distractor contrast varied freely. We studied the benefits of cueing all item locations with yellow boxes drawn around each item. In both experiments, 24-item search displays were presented twice. Experiment 1 had 384 unique displays. Half of the displays were first presented cued and then uncued (Cue–NoCue), for the other half this order was reversed (NoCue–Cue). Experiment 2 had 288 unique displays. Half the displays were presented NoCue–Cue, the other half as NoCue–NoCue. Both experiments found the same result for present trials: cueing reduced the error rates for the lowest contrast targets (15), without increasing RTs. In Experiment 1, cueing did not change RTs or accuracy for higher contrast targets (45, 75, 105). In Experiment 2, cueing did not improve accuracy for higher contrasts (45, 75) either, but RTs slowed down. For the absent trials both experiments did not find any effect of cueing on either accuracy or RTs. Looking at eye movement data, we can characterize errors as “search” errors where the observer never fixates the target and “recognition” errors where the target is fixated but the eyes move away without registering it successfully. Cueing all potential targets reduced misses by reducing “search” errors in both experiments. Specifically, low contrast targets were more likely to be visited. We conclude that cueing directs attention to items, rather than enhancing their processing once attention arrives. Encouragingly, the accuracy gain from cueing does not necessarily come with an RT cost.

Acknowledgements: JH and AL were supported by UKRI grant ES/X000443/1. JMW was supported by NIH-NEI: EY017001, NSF: 2146617, and NIH-NCI: CA207490