Object-substitution masking weakens but does not eliminate shape interactions

Abstract

At any moment, some objects in the environment are seen clearly, whereas others go unnoticed. Whether or not these gaps in awareness are actually problematic may depend on the extent that information about unseen objects is lost. Determining when and how visual awareness and visual processing become linked is thus of great importance. Previous research using object-substitution masking (OSM) demonstrated that relatively simple visual features, such as size or orientation, are still processed even when they are not visible. Yet this does not appear to be the case for more complex features like faces. This suggests that, during OSM, disruptions of visual processing and awareness may tend to co-occur beginning at some intermediate stage along the ventral pathway. We tested this hypothesis by evaluating the extent to which OSM disrupted the perception and processing of two-dimensional objects. Specifically, we evaluated whether an unseen shape's aspect ratio would influence the appearance of another shape that was briefly visible nearby. As expected, the aspect ratios of two shapes appeared to be more similar to each other when both were visible. This averaging effect was weakened, but not eliminated, when one ellipse in each pair received OSM. These shape interactions persisted even when one ellipse from each pair was invisible. When combined with previous work, these results suggest that during object-substitution masking, disruptions of visual processing tend to strengthen with increases in stimulus complexity, becoming more tightly bound to the mechanisms of visual awareness at intermediate stages of visual analysis.

Integration and segmentation conflict during ensemble coding of shape.

“…This is a perceptual consequence of segmentation—objects are perceived to be more distinct than they really are. Similar distortions have been observed for perception of size (Fortenbaugh, Sugarman, Robertson, & Esterman, 2019), shape (Sweeny, D’Abreu, Elias, & Padama, 2017), spatial location (Badcock & Westheimer, 1985; DiGiacomo & Pratt, 2012; Suzuki & Cavanagh, 1997), and direction of motion (Thornton, 2002). Segmentation is likely involved in distinguishing figure (i.e., object) from ground (i.e., background; Grossberg, 1994; Westheimer & Levi, 1987) and can even act at during decision-making (Fritsche & de Lange, 2019; Zamboni, Ledgeway, McGraw, & Schluppeck, 2016).…”

Ensemble perception includes information from multiple spatial scales

“…We found no evidence that the integration of global organizations into ensemble representations depended on whether those global organizations were masked. This is consistent with recent findings that information about global form can be processed even when it is suppressed from awareness (Chung & Khuu, 2014;Mudrik et al, 2011), as well as our previous work in which we found that global organization biased perception of individual shapes, even when they were masked out of awareness (Sweeny et al, 2017). Ensemble representations have been shown to sometimes include visual information about which a perceiver is unaware (Fischer & Whitney, 2011;Parkes et al, 2001).…”

“…This may seem like a surprising prediction, but in fact we found in a previous investigation that global organizations only distorted perception of individual shapes when those shapes had tall aspect ratios (Sweeny, Grabowecky, & Suzuki, 2011b). Finally, in our previous work we found that global organizations biased perception of individual shapes even when they were not visible (Sweeny et al, 2017). We thus predicted that, here, global aspect ratio would still bias perception of a set's average shape in the masked condition, but potentially with reduced strength compared to the unmasked condition.…”

“…By masking these, but not the other four shapes, we aimed to disrupt perception of global organizations, more generally, and then determine whether these hidden global organizations could nevertheless influence local estimates of ensemble aspect ratio. This question is worth askinginformation about global form is known to be processed even when it is suppressed from awareness (Chung & Khuu, 2014;Mudrik et al, 2011), masked global organizations can bias perception of individual shapes (Sweeny et al, 2017), and ensemble representations may include visual information about which a perceiver is unaware (Fischer & Whitney, 2011;Parkes et al, 2001). We note that this question was of secondary interest to us, since answering it would only be of value if we first found an effect of global integration without masking (our primary aim).…”

“…Second, ensemble coding is known to operate for perception of aspect ratio (Elias & Sweeny, 2020). Third, global-to-local interactions occur during the perception of shape (e.g., the spatial organization of a set of objects can bias perception of individual aspect ratios in the set) (Sweeny et al, 2011a;Sweeny et al, 2017). Fourth, interesting local distortions emerge during the perception of aspect ratio.…”