Abstract
The ability to make fine localization judgments is crucial for interaction with objects in our environment. Although retinotopic representations of object locations are an important component of stimulus localization, a large body of work has shown that other factors, such as motion, attention, and frames of reference play an important role as well. While previous studies have described how these factors influence perceived locations across groups of observers, individual differences in perceptual localization remain poorly understood. In the present study, we performed a series of experiments to map individual differences in perceived position. On each trial, subjects were shown a 50 ms random dot noise pattern within a Gaussian contrast envelope. Angular stimulus position varied randomly along a 7 degree invisible isoeccentric ring. Subjects reported the target's position by adjusting a cursor to its location. We found that subjects demonstrate idiosyncratic patterns of response error (up to 10-15° of rotation angle at a single location) and that these patterns are stable across multiple testing sessions. Correlations of mean response error across the set of stimulus locations were high across testing sessions within each subject (r = .63), but low between subjects (r = -.03). We also demonstrated that these patterns were robust to changes in response method, as subjects' errors in the adjustment task correlated with those in a separate 2AFC task in which subjects compared the positions of stimuli across two intervals (r = .66). Finally, we demonstrate that perceived position correlated with subjects' saccade errors as they made speeded saccades to the same targets. Together, our results provide novel evidence for stable idiosyncratic patterns of perceptual distortions across observers and demonstrate the importance of measuring individual differences in perceived location.
Meeting abstract presented at VSS 2014