Relationship between selective visual attention and visual consciousness

The relationship between attention and consciousness is a close one, leading many scholars to conflate the two. However, recent research has slowly corroded a belief that selective attention and consciousness are so tightly entangled that they cannot be individually examined. We distinguish between exogenous, saliency-driven, task-independent attention and top-down, endogenous and voluntary attention. In the first part we will summarize powerful computational models of saliency-driven attention that capture a large fraction of eye movements in normal subjects inspecting natural scenes. In the second part, we will summarize psychophysical and neurophysiological evidence arguing that top-down attention and consciousness are distinct phenomena that need not occur together and that can be manipulated using distinct paradigms. Subjects can become conscious of an isolated object, or the gist of the scene in the near absence of top-down attention. Conversely, subjects can attend to perceptually invisible objects. We also cover the recent flurry of studies that utilized independent manipulation of attention and consciousness. These studies have shown paradoxical effects of attention, including examples where top-down attention and consciousness have opposing effects. These data provide clear evidence for distinctive influence of attention and consciousness on perception. We argue that the dissociation is consistent with the following consideration of functions of attention and consciousness. The visual system is constantly bombarded with information, leading to a data deluge that cannot be processed in real time; on the order of one megabyte of raw information exits the retina every second. The prime goal of visual attention therefore is to select information to meet current behavioral goals. By definition this implies a relative decrease of processing resources for non-attended Keynote Paper