Online research in philosophy

Because the visual system cannot process all of the objects, colors, and features present in a visual scene, visual attention allows some visual stimuli to be selected and processed over others. Most research on visual attention has focused on spatial or location-based attention, in which the locations occupied by stimuli are selected for further processing. Recent research, however, has demonstrated the importance of objects in organizing (or segregating) visual scenes and guiding attentional selection. Because of the long history of spatial attention research, theories of spatial attention are more mature than theories of other visual processes, such as object segregation and object attention. In the present paper, I outline a biased competition account of object segregation and attention, following similar accounts that have been developed for spatial attention (Desimone and Duncan, 1995). In my biased competition account, I seek to understand how some objects can be segregated and selected over other objects in a complex visual scene. Under this account, there are two sources of visual information that allow an object to be processed over other objects: bottom-up information carried by the physical stimulus and top-down information based on an observer's goals. I use the biased competition account to combine many diverse findings from the object segregation and attention literatures into a common framework.

Pylyshyn acknowledges that cognition intervenes in determining the nature of perception when attention is allocated to locations or properties prior to the operation of early vision. I present evidence that scale perception (one function of early vision) is cognitively penetrable and argue that Pylyshyn's criterion covers not a few, but many situations of recognition. Cognitive penetrability could be their modus operandi.

The processes whereby our brains continue to learn about a changing world in a stable fashion throughout life are proposed to lead to conscious experiences. These processes include the learning of top-down expectations, the matching of these expectations against bottom-up data, the focusing of attention upon the expected clusters of information, and the development of resonant states between bottom-up and top-down processes as they reach an attentive consensus between what is expected and what is there in the outside world. It is suggested that all conscious states in the brain are resonant states and that these resonant states trigger learning of sensory and cognitive representations. The models which summarize these concepts are therefore called Adaptive Resonance Theory, or ART, models. Psychophysical and neurobiological data in support of ART are presented from early vision, visual object recognition, auditory streaming, variable-rate speech perception, somatosensory perception, and cognitive-emotional interactions, among others. It is noted that ART mechanisms seem to be operative at all levels of the visual system, and it is proposed how these mechanisms are realized by known laminar circuits of visual cortex. It is predicted that the same circuit realization of ART mechanisms will be found in the laminar circuits of all sensory and cognitive neocortex. Concepts and data are summarized concerning how some visual percepts may be visibly, or modally, perceived, whereas amodal percepts may be consciously recognized even though they are perceptually invisible. It is also suggested that sensory and cognitive processing in the What processing stream of the brain obey top-down matching and learning laws that are often complementary to those used for spatial and motor processing in the brain's Where processing stream. This enables our sensory and cognitive representations to maintain their stability as we learn more about the world, while allowing spatial and motor representations to forget learned maps and gains that are no longer appropriate as our bodies develop and grow from infanthood to adulthood. Procedural memories are proposed to be unconscious because the inhibitory matching process that supports these spatial and motor processes cannot lead to resonance.

Artists, art critics, art historians, and cognitive psychologists have asserted that visual artists perceive the world differently than nonartists and that these perceptual abilities are the product of knowledge of techniques for working in an artistic medium. In support of these claims, Kozbelt (2001) found that artists outperform nonartists in visual analysis tasks and that these perceptual advantages are statistically correlated with drawing skill. We propose a model to explain these results that is derived from a diagnostic framework for object recognition and recent research in cognitive neuroscience on selective visual attention. This research demonstrates that endogenous shifts of visual attention enhance the encoding of expected features in the visual field and inhibit the perception of potential distracters. Moreover, it demonstrates complementary roles for spatial schemata and motor plans in visual attention. We argue that artists develop novel spatial schemata, which enable them to recognize and reproduce stimulus features sufficient for adequate artistic production in a medium, and that these schemata become encoded as motor plans as artists develop technical proficiency in a medium. We hypothesize that artists' perceptual advantages can therefore, be explained by the role spatial schemata and motor plans play in selective attention.

Pylyshyn's argument is very similar to one made in the 1960s to the effect that vision may be influenced by spatial selective attention being directed to distinctive stimulus features, but not by mental set for meaning or membership in an ill-defined category. More recent work points to a special role for spatial attention in determining the contents of perception.