Online research in philosophy

Experiments on scene perception and change blindness suggest that the visual system does not construct detailed internal models of a scene. These experiments therefore call into doubt the traditional view that vision is a process in which detailed representations of the environment must be constructed. The non-existence of such detailed representations, however, does not entail that we do not perceive the detailed environment. The “grand illusion hypothesis” that our visual world is an illusion rests on (1) a problematic “reconstructionist” conception of vision, and (2) a misconception about the character of perceptual experience.

Experiments on scene perception and change blindness suggest that the visual system does not construct detailed internal models of a scene. These experiments therefore call into doubt the traditional view that vision is a process in which detailed representations of the environment must be constructed. The non-existence of such detailed representations, however, does not entail that we do not perceive the detailed environment. The “grand illusion hypothesis” that our visual world is an illusion rests on (1) a problematic “reconstructionist” conception of vision, and (2) a misconception about the character of perceptual experience.

The psychological concept of illusion is defined as a process involving an interaction of logical and empirical considerations. Common usage suggests that an illusion is a discrepancy between one's awareness and some stimulus. Following preliminary definitions of classes of stimuli, five definitions of illusion are considered, based upon the possible discrepancies between awareness and a stimulus. It is found that each of these definitions fails to make important distinctions, even to the point of equating all illusory and perceptual phenomena. This dilemma is resolved by redefining illusion without reference to truth or falsity, but relative to the functioning of a given perceptual system under different conditions. The definition accepted as best is 'a discrepancy between one's perceptions of an object or event observed under different conditions'. Conditions may differ in terms of stimulus exposure, stimulus context, or experiental context. The philosophical and psychological implications are discussed of accepting a definition of illusion not based on a discrepancy between awareness and a stimulus.

Throughout history there have been people who say it is all illusion. I think they may be right. But if they are right what could this mean? If you just say "It's all an illusion" this gets you nowhere - except that a whole lot of other questions appear. Why should we all be victims of an illusion, instead of seeing things the way they really are? What sort of illusion is it anyway? Why is it like that and not some other way? Is it possible to see through the illusion? And if so what happens next.

The persistence of certain illusions has been used to argue that some theories cannot affect our perceptual experiences. Learning that one of these illusions is an illusion involves accepting theories. Nevertheless, the illusion does not go away. It seems then that these theories cannot affect our perceptual experiences. This paper contests an assumption of this argument: that the only way in which our perceptions can be affected by holding these theories is by the illusion going away.

In recent years, a pair of intriguing phenomena has caused researchers working on vision and visual attention to reevaluate many of their assumptions. These phenomena, which have come to be called change blindness (CB) and inattentional blindness (IB), have led many to the conclusion that ordinary perceivers labor under a ``grand illusion'' concerning perception - an illusion that is..