Intrinsic position uncertainty explains detection and localization performance in peripheral vision

Abstract

Efficient performance in visual detection tasks requires excluding signals from irrelevant spatial locations. Indeed, researchers have found that detection performance in many tasks involving multiple potential target locations can be explained by the uncertainty the added locations contribute to the task. A similar type of Location Uncertainty may arise within the visual system itself. Converging evidence from hyperacuity and crowding studies suggests that feature localization declines rapidly in peripheral vision. This decline should add inherent position uncertainty to detection tasks. The current study used a modified detection task to measure how intrinsic position uncertainty changes with eccentricity. Subjects judged whether a Gabor target appeared within a cued region of a noisy display. The eccentricity and size of the region varied across blocks. When subjects detected the target, they used a mouse to indicate its location. This allowed measurement of localization as well as detection errors. An ideal observer degraded with internal response noise and position noise (uncertainty) accounted for both the detection and localization performance of the subjects. The results suggest that position uncertainty grows linearly with visual eccentricity and is independent of target contrast. Intrinsic position uncertainty appears to be a critical factor limiting search and detection performance.

Apparent Motion Suppresses Responses in Early Visual Cortex: A Population Code Model

“…Spatial uncertainty, for instance, has been found to increase the steepness of the psychometric function [35]. Notably, spatial uncertainty is higher in the periphery compared to the fovea [36, 37]. In our experiment, the target was positioned relatively far in the periphery (i.e., 10°), making it possible that uncertainty contributed to the steepness of the psychometric functions.…”

Linking V1 Activity to Behavior

“…However, human subjects are poor at judging the location of stimuli away from the fovea, demonstrating that information about precise location is lost along the visual processing stream. This intrinsic spatial uncertainty is substantial—it increases linearly with eccentricity and has a radius at half height of ∼15% of the eccentricity (Michel & Geisler 2011). Such an intrinsic uncertainty, which is likely to extend to stimulus dimensions other than spatial position, is an important form of pooling inefficiency that contributes to suboptimal performance in many tasks and could have contributed to the inefficient decoding reported by Chen et al (2006, 2008) and Michelson & Seidemann (2012).…”

“…Human subjects are poor at isolating and discriminating individual elements from multi-element displays presented in the periphery even when the elements are sufficiently small and far apart to support independent representations in V1 (for a review, see Pelli 2008). While intrinsic spatial uncertainty and crowding are conceptually related, their specific properties suggest that they are caused by different forms of pooling inefficiencies (Michel & Geisler 2011). …”

Multisensory stimuli improve relative localisation judgments compared to unisensory auditory or visual stimuli

“…It was hypothesised that when comparing the ability to make auditory and visual relative localisation judgments with perceptually matched stimuli, visual performance would exceed auditory in central locations (i.e., at the fovea). However, visual localisation acuity declines linearly with eccentricity (Michel and Geisler, 2011), whereas the decline in auditory localisation cues is more modest with cues remaining robust across a range of eccentricities (Macpherson and Middlebrooks, 2002; Wood and Bizley, 2015). We therefore predicted that at more peripheral locations auditory relative localisation judgments might be more accurate than visual.…”