Abstract
Perceiving the positions of objects is a prerequisite for most other visual and visuomotor functions. Although stable, consistent, and accurate localization is frequently assumed to be a simple product of retinotopic position, a recent study found that each individual observer mislocalizes the positions of briefly presented objects throughout the visual field in a unique way (Kosovicheva & Whitney, 2017). Within each observer, some regions of the visual field are effectively compressed and other regions are expanded. Previous work demonstrated that these regions of compression and expansion are closely associated with higher spatial acuity and lower spatial acuity, respectively. This suggests that heterogeneous spatial resolution across the visual field might be the underlying mechanism of these individualized distortion fingerprints of position perception (Wang, Murai, Whitney, VSS, 2019; in prep). Are these biases caused by astigmatism and are they inherited along the visual hierarchy such that they change object appearance? Here, we show that the idiosyncratic biases are not due to astigmatism, since previous research revealed that individuals have distinct axes of astigmatism in their two eyes (McKendrick & Brennan, 1997), but our results demonstrated that the distortion fingerprints remained consistent when stimuli were viewed in either eye or binocularly. However, we did find that individualized spatial distortion biases modulate perceived object size. Using the method of single stimuli, we measured the perceived size of a briefly presented arc. The apparent size of the arc was associated with idiosyncratic visual space distortion patterns: Objects were perceived to be larger at perceptually compressed locations and smaller at expanded areas. Together, our study suggests that idiosyncratic spatial distortions induced by heterogeneous spatial acuity can influence visual appearance of object size or shape.