Seven myths on crowding and peripheral vision

Abstract

Crowding has become a hot topic in vision research and some fundamentals are now widely agreed upon. For the classical crowding task, one would likely agree with the following statements. (1) Bouma’s law can, succinctly and unequivocally, be stated as saying that critical distance for crowding is about half the target’s eccentricity. (2) Crowding is predominantly a peripheral phenomenon. (3) Peripheral vision extends to at most 90° eccentricity. (4) Resolution threshold (the minimal angle of resolution, MAR) increases strongly and linearly with eccentricity. Crowding increases at an even steeper rate. (5) Crowding is asymmetric as Bouma has shown. For that inner-outer asymmetry, the peripheral flanker has more effect. (6) Critical crowding distance corresponds to a constant cortical distance in primary visual areas like V1. (7) Except for Bouma’s seminal paper in 1970, crowding research mostly became prominent starting in the 2000s. I propose the answer is ‘not really’ or ‘not quite’ to these assertions. So should we care? I think we should, before we write the textbook chapters for the next generation.

Mixture model investigation of the inner-outer asymmetry in visual crowding reveals a heavier weight towards the visual periphery

“…Surprisingly, using a letter identification task, they observed a reverse inner-outer asymmetry. That is, observers confused the target with the inner letter, which was less impaired by pooling processes compared to the outer letter 35 . In contrast to Strasburger and Malania (2013) 34 , our findings support the substitution model.…”

“…Namely, in a letter identification task, in which three letters were presented on the horizontal meridian instead of the target (the middle one), observers often reported the inner letter more than the outer letter 34 . To explain this conflicting result, Strasburger 35 assumed a pooling process-under crowding, due to inappropriate integration field size in the periphery, observers simultaneously detect and pool excessive information of low-level features, including those that belong to the flankers 5,18,[36][37][38][39][40] . These pooling models suggest that crowding reflects some type of integration or averaging of target and flanker features.…”

“…These pooling models suggest that crowding reflects some type of integration or averaging of target and flanker features. According to Strasburger, observers reported the inner flanker because it was less affected by the integration field and, therefore, more intact compared to the target and the outer flanker 35 .…”

On the cortical mapping function – visual space, cortical space, and crowding

“…Finally, the cortical location function can be used (perhaps unexpectedly) to derive the cortical distances in visual crowding. Crowding happens when neighboring patterns to a target stimulus are closer than a critical distance, where the latter can be described by Bouma's law (Bouma, 1970;Pelli & Tillman, 2008;Strasburger, 2020). We thus arrive at a cortical version of Bouma's law.…”

“…Crowding is the phenomenon of impaired recognition of a pattern in the presence of neighboring patterns. It is the prominent characteristic of peripheral vision yet is equally important in the fovea (Strasburger, 2020). Remarkably, unlike typical perceptual tasks like acuity where critical size scales with eccentricity, crowding is mostly independent of target size (Pelli, Palomares, & Majaj, 2004;Whitney & Levi, 2011).…”