Seeing Absences: A Role for Memory in Perception
University of North Carolina at Chapel Hill
Intuitively, we often see absences. For example, if someone steals your laptop at a café, you may see its absence from your table. However, absence perception presents a paradox. On prevailing models of perception, we see only present objects and scenes (Marr, Gibson, Dretske). So, we cannot literally see something that is not present. This suggests that we never literally perceive absences; instead, we come to believe that something is absent cognitively on the basis of what we perceive. But this cognitive explanation does not do justice to the phenomenology. Many experiences of absence possess immediate, perceptual qualities. One may further argue that the ability to detect certain absences confers strong adaptive advantage and therefore must be as primitive and fundamental to humans as seeing positive things.
In this paper, I argue that we can literally see absences; in addition to representing objects, perception represents absences of objects. I use the paradigm of failed visual searches as a basis for a general model of seeing absence. According to this model, seeing absence of object O consists in a mismatch between O’s image constructed in visual working memory and the observed positive stimulus. This has important implications for the role of imagery in perception. It has been previously shown that imaginative projections can restore missing sensory information and thus virtually “complete” present objects; or, they can inform what the non-present objects are like. On the current account, imagery does not merely represent sensory objects in their absence; it also represents their absences via a mismatch.
The phenomenon of seeing absence can thus serve as an adequacy-test for a theory of perceptual content. If experiences of absence are possible, then we have another reason (following Siegel) to reject the view that perceptual content is restricted to colors and shapes. And, if the current account of seeing absence is correct, we have additional support for the argument that perception involves imagination. Finally, the account has explanatory benefits because it allows us to distinguish seeing absence from other types of imagery-based phenomena, like nonveridical seeing (hallucinations) and virtual seeing (“perceptual presence-in-absence”, Noë, Macpherson).