Kaila Dowd¹, Kamilla Volkova¹, Michael Grubb¹; ¹Trinity College

Visual crowding is a perceptual phenomenon in which a peripheral stimulus is identified more easily when presented in isolation than when surrounded by flankers. To ensure that stimuli appear in the periphery, eye-tracking is essential. Here we leveraged the eye-tracking capabilities of the Apple Vision Pro, a relatively cheaper and immensely more portable alternative to commercial eye-trackers, to demonstrate a feasible use case of the Apple Vision Pro for visual psychophysics. In this project, we measure crowding and replicate the finding that covert exogenous spatial attention reduces the critical distance. On each trial, we presented a target T at one of four possible orientations, which was flanked above and below by Hs or Is. Then, participants reported the orientation of the T, with their eyes and a finger tap. We used eight distinct spacings between the target and flankers. Before the stimulus array, a brief onset appeared in either the same (valid condition) or opposite (invalid condition) hemifield, eliciting the reflexive allocation of covert spatial attention. Fourteen participants completed the study. For each participant and each attention condition, we calculated proportion correct at each spacing and fitted an exponential model to the data to obtain the parameters needed to calculate the critical distance for each cue type. The Wilcoxon signed rank test verified that valid cues resulted in a lower critical distance than invalid cues. We also ran a 2x8 repeated measures ANOVA where we found significant main effects of cue type and stimuli spacing on accuracy. In short, we were able to successfully measure visual crowding and replicate previous work on the impact of exogenous cueing using the Apple Vision Pro. This is an exciting proof-of-principle demonstration, attesting to the possibility of using cheap, portable, and immersive VR systems for visual psychophysics in a diversity of settings.

Acknowledgements: Supported by NSF-2141860 CAREER to MAG