Uncertainty Of Attention And Visual Experience

Visual attention plays an important role in epistemology. You come to know about things you see by paying attention to them, and thereby taking them up in thought and belief. Recent work in the cognitive sciences shows that attention also has a quite different role. Attention dictates not only what you take up in thought and belief, but also how things appear to you in visual experience. Attention enhances the neural signal that's processed for attended aspects of a scene, and so highlights those aspects by changing their visual appearance. For example, drawing attention to a colour makes it appear more saturated; drawing attention to a shape makes it appear larger. This raises a challenge for the epistemology of attention. It threatens to show that attention is a systematic source of illusion, rather than a reliable source of knowledge. Indeed, some scientists working in the area draw that conclusion.

To meet this challenge, I argue that visual experience is experience of determinable properties: properties which admit of more specific determinations, as red is determined by crimson, and 90 to 110 feet long is determined by 100 feet long. One determinate property determines many determinable properties. So one determinate shape or colour may take on different appearances, in veridical experiences of its different determinables. And one determinable property has many determinates. So different determinate properties may share an appearance, in veridical experiences of one determinable which they all determine.