Perceptual Errors Support the Notion of Masking by Object Substitution

Abstract

Two experiments examined the effect of Object Substitution Masking (OSM) on the perceptual errors in reporting the orientation of a target. In Experiment 1 a four-dot trailing mask was compared with a simultaneous-noise mask. In Experiment 2, the four-dot and noise masks were factorially-varied. Responses were modelled using a mixture regression-model and Bayesianinference to deduce whether the relative impacts of OSM on guessing and precision were the same as those of a noise mask, and thus whether the mechanism underpinning OSM is based on increasing noise rather than a substitution process. Across both experiments, OSM was associated with an increased guessing-rate when the mask trailed target offset, and a reduction in the precision of the target representation (although the latter was less reliable across the two experiments). Importantly, the noise mask also influenced both guessing and precision, but in a different manner, suggesting that OSM is not simply caused by increasing noise. In Experiment 2 the effects of OSM and simultaneous-noise interacted, suggesting the two manipulations involve common mechanisms. Overall results suggest that OSM is often a consequence of a substitution process, but there is evidence that the mask increases noise levels on trials where substitution doesn't occur.

Common-onset masking terminates the temporal evolution of orientation repulsion

“…Second, two theories assuming object-level interferences between the target and mask are considered: object substitution theory (e.g., Di Lollo et al, 2000 ; Kahan & Lichtman, 2006 ; Pilling et al, 2019 ) and object updating theory (e.g., Goodhew, 2017 ; Lleras & Moore, 2003 ; Pilling & Gellatly, 2010 ). As the differences between these theories are subtle and the present study did not aim to differentiate them, we tentatively consider the object updating theory as a working hypothesis because it imposes looser constraints on the mechanism of common-onset masking compared to the object substitution theory.…”

“…Based on observations that metacontrast masking peaks at positive SOAs (when the target precedes the mask), several influential models have been proposed (Bachmann, 1984;Breitmeyer & Ganz, 1976;Breitmeyer & Ögmen, 2000). (Bridgeman, 1971;Francis, 1997), a sparse mask-such as four dots-remotely surrounding the target is mainly used in common-onset masking (e.g., Di Filmer, Mattingley, & Dux, 2014;Llears & Moore, 2003;Pilling, Guest, & Andrews, 2019).…”

“…Even though the target is easily seen when the target and mask are extinguished simultaneously, it becomes more difficult to see the target as the mask remains after the target offset. To avoid contour-based inhibitions that probably dominate metacontrast ( Bridgeman, 1971 ; Francis, 1997 ), a sparse mask—such as four dots—remotely surrounding the target is mainly used in common-onset masking (e.g., Di Lollo et al, 2000 ; Filmer, Mattingley, & Dux, 2014 ; Llears & Moore, 2003 ; Pilling, Guest, & Andrews, 2019 ).…”

The independence of endogenous attentional orienting and object individuation.

“…Of course, it is worth noting that some recent studies have claimed to support the object-substitution account, but although this evidence is consistent with the model, it is also consistent with other models—that is, it is not theory-diagnostic. For example, it has been found that OSM operates on an all-or-none rather than a graded perceptual basis (Pilling, Guest, & Andrews, 2019). This could be considered consistent with the object-substitution account, but such a finding is in no way exclusive to the object-substitution account.…”