Biasmapping: Idiosyncratic covert search in the vicinity of fixation.

In free visual search, individuals move their eyes around a scene and search for targets with a "functional visual field" (FVF) surrounding the current point of fixation. Items could be sampled in series, one after the other within the FVF or the entire FVF might be processed in parallel. In either case, processing could be uniform, on average, across the FVF or, alternatively, some items or regions in the FVF might be systematically processed more successfully than others. To assess this, we had observers fixate at a point and then flashed a ring of eight items around fixation. We examined the distribution of errors as a function of the angular position around fixation. We found, as might be expected, that, on average, fewer errors were made on the horizontal than on the vertical meridian. Interestingly, we found reliable, idiosyncratic deviations from this average pattern. Observers tended to have specific angular positions that were consistently better or worse than average. These biases in search performance might be related to the production of otherwise apparently random false negative errors in visual search. (PsycInfo Database Record (c) 2026 APA, all rights reserved).