Substituting objects from consciousness: A review of object substitution masking

Abstract

Object substitution masking (OSM) occurs when a sparse (e.g., four-dot), temporally trailing mask obscures the visibility of a briefly presented target. Here, we review theories of OSM: those that propose that OSM reflects the interplay between feedforward and feedback/reentrant neural processes, those that predict that feedforward processing alone gives rise to the phenomenon, and theories that focus on cognitive explanations, such as object updating. We discuss how each of these theories accommodates key findings from the OSM literature. In addition, we examine the relationship between OSM and other visual-cognitive phenomena, including object correspondence through occlusion, change blindness, metacontrast masking, backward masking, and visual short-term memory. Finally, we examine the level of processing at which OSM impairs target perception. Collectively, OSM appears to reflect the conditions under which the brain confuses two visual events for one when they are encoded with low spatiotemporal resolution, due to processing resources being otherwise occupied.Keywords Object substitution masking . Attention . Reentrant processing . Consciousness When observing a visual scene, at any point in time, we are conscious of only a small fraction of the available information. Given this limitation, it is important to understand the mechanisms that determine what stimuli we become conscious of, when we become conscious of them, and the nature of processing that occurs in the absence of explicit awareness. There exists a long and rich history in experimental psychology of using visual masking to explore such issues. Visual masking refers to conditions where the visibility of one to-be-reported visual stimulus (the target) is obscured by the presentation of another stimulus (the mask) that appears in close spatiotemporal proximity and does not require report. Object substitution masking (OSM) is a recent discovery in the field of visual masking and is an ideal tool for exploring questions about visual awareness because it selectively impairs the extent to which an individual becomes conscious of a visual stimulus without the extent of image-level degradation that other forms of visual masking induce. This review, therefore, focuses on the determinants and consequences of visual awareness in OSM.Here, we integrate a diverse range of literature to discern what OSM can tell us about perceptual consciousness and visual cognition in general. Specifically, we discuss the role of feedforward versus feedback processing in giving rise to OSM, whether the phenomenon is better characterized as reflecting object updating or object substitution, the similarities and differences between OSM and other forms of masking, and OSM's relationship to other visual-cognitive phenomena. In addition, we review evidence regarding the role of attention in masking. Our aim is to address controversies in the OSM literature in depth and offer insights into how some of them may already be resolved and how the field might go about resolving ...

Size (mostly) doesn’t matter: the role of set size in object substitution masking

“…The implications of these findings are considerable. If ceiling effects have been driving the interaction between attention and masking magnitude, then the role of attention is OSM is likely to be different to that previously presumed in the numerous models of OSM that have been developed (Goodhew et al, 2013). Thus, this will impact upon our conceptualization of OSM and the mechanisms hypothesised to underlie the phenomenon and, indeed, other forms of masking.…”

“…However, if the mask offset is delayed relative to that for the target, visibility of the target is reduced. OSM is thought to reflect the dynamics of reentrant neural processing (Fahrenfort, Scholte, & Lamme, 2007a;Fahrenfort, Scholte, & Lamme, 2007b;Fahrenfort, Scholte, & Lamme, 2005;Lamme & Roelfsema, 2000;Lamme, Super, & Spekreijse, 1998), where feedforward and feedback neural signals interact to resolve incongruent perceptual hypotheses at different levels of information processing (Di Lollo, Enns, & Rensink, 2000;Dux, Visser, Goodhew, & Lipp, 2010;Goodhew, Pratt, Dux, & Ferber, 2013;Jannati, Spalek, & Di Lollo, 2013). Specifically, visual information is fed from primary visual cortex to higher-level regions.…”

“…A long held view is that without dispersed attention OSM is not observed (Dux et al, 2010;Enns, 2004;Goodhew et al, 2013). Spatial attention in OSM paradigms has been manipulated in several different ways, but the typical approach is to vary the number of distractor items displayed along with the target stimulus.…”

Tuning perception: Visual working memory biases the quality of visual awareness

“…They used objectsubstitution masking (OSM) (Enns & Di Lollo, 1997), in which the visibility of a target item is impaired by a sparse four-dot mask that has a delayed offset from the target (for a review, see Goodhew et al, 2013). Harrison and colleagues (2015) found that the precision of a visual representation was affected by the presence and timing of a mask.…”

Odours reduce the magnitude of object substitution masking for matching visual targets in females

“…According to one prominent theory, OSM occurs due to a conflict between the target object and the mask at different stages of visual processing, reflecting re-entrant processing between primary visual cortex (V1), other areas of occipital cortex and higher cortical areas in the temporal and parietal lobes (Di Lollo, Enns, & Rensink, 2000;Dux, Visser, Goodhew, & Lipp, 2010). Another account, the object updating hypothesis, suggests that OSM is caused by a failure in individuation of the target and the mask (Lleras & Moore, 2003;Pilling & Gellatly, 2010), possibly due to limitations in the temporal resolution of visual encoding (Goodhew, Pratt, & Dux, 2013). Carlson, Rauschenberger, and Verstraten (2007) found that neural responses to repeated targets subject to OSM reflected adaptation in V1 but not lateral occipital cortex, suggesting the neural representation of the masked target object was reduced, if not completely suppressed, in ventral occipital cortex.…”