Cailey Tennyson¹ (), Injae Hong¹, Rawan Ne'meh², Jeremy Wolfe^1,3; ¹Brigham and Women's Hospital, ²Hariri High School 2, Beirut, Lebanon, ³Harvard Medical School

In a 250-300msec fixation, you can attend to ~4-6 nearby items. If there are more candidates in the neighborhood, choices must be made. In prior work, observers moved their eyes to a fixation spot when it moved to a new location. A ring of one T and seven Ls was flashed around the spot after 300 msec. Observers made 4AFC assessments of the T’s orientation. Flash duration was adjusted to produce ~25% errors. There was an average non-uniformity in the distribution of errors with more errors on the vertical meridian. More interestingly, there were often significant idiosyncratic deviations from that average. To find out if patterns of deviations were stimulus-specific, we repeated the TvsL condition and added a search for a hammer among seven different tool silhouettes. Observers ran 360 trials for each task in four, 180 trial sessions. The TvsL condition replicated prior results with 17 of 20 observers showing significant deviations from the average result. Moreover, patterns were quite consistent with an r=0.6 correlation of session 1 with session 2. Tools showed a more dramatic average deviation with ~26% of all errors at the bottom of the ring of locations. Only 10 of 20 observers showed significant idiosyncratic deviations from this pattern. Observers were strongly consistent between sessions (r=0.73). There was also a reasonable correlation between TvL and Tool tasks (r=0.39). We conclude that there are idiosyncratic variations in the deployment of attention in the vicinity of the current point of fixation. These appear to be quite different from the inhomogeneities in sensitivity to visual stimuli (e.g. Himmelberg, Winawer, & Carrasco, TINS, 2023). The choice of stimuli modulates the patterns of errors for reasons that are not entirely clear. These idiosyncratic relative attentional blindspots at different locations relative to fixation could contribute to errors in visual search.

Acknowledgements: NEI EY017001, NSF 2146617