Maintaining the ties that bind: The role of an intermediate visual memory store in the persistence of awareness

Abstract

Segregation and feature binding are essential to the perception and awareness of objects in a visual scene. When a fragmented line-drawing of an object moves relative to a background of randomly oriented lines, the previously hidden object is segregated from the background and consequently enters awareness. Interestingly, in such shape-from-motion displays, the percept of the object persists briefly when the motion stops, suggesting that the segregated and bound representation of the object is maintained in awareness. Here, we tested whether this persistence effect is mediated by capacity-limited working-memory processes, or by the amount of object-related information available. The experiments demonstrate that persistence is affected mainly by the proportion of object information available and is independent of working-memory limits. We suggest that this persistence effect can be seen as evidence for an intermediate, form-based memory store mediating between sensory and working memory.

The authors would like to acknowledge Kendra Hollidge and Justin Ruppel for assistance with data collection. Sincere thanks also to Maha Adamo and Arin Klug for helpful comments. This research was supported by a Natural Sciences and Engineering Research Council of Canada (NSERC) grant awarded to the first author.

Notes

¹ The term “binding” can refer to integration of information both within a dimension (e.g., binding line-segments into contours) and between arbitrary dimensions (e.g., form and colour). While binding is often discussed in general terms, Humphreys (2001) argues that binding is a multistage process based on neuropsychological evidence from patients with lesions to areas of either the ventral or dorsal visual streams: binding of form elements into contours, binding of contour information into holistic shapes, and binding of shape to surface detail. According to this distinction, binding in SFM can refer to either of the first two of these stages.