It takes deliberate effort to become more aware of everyday visual perception as a code. However, a simple experiment allows us to 'bracket' visual perception at least briefly. For this to be possible, you need to sit facing the same direction without moving your body for a few minutes: Gaze blankly at the space in front of you. Avoid 'fixing' the space into objects and spaces between objects; instead, try to see it as a continuum of impressions. If the necessary degree of purposelessness is achieved, the space will lose its familiar properties. Instead of receding in depth, it will seem to float dimensionless from the bottom to the top of the field of vision. A rectangular book, instead of lying flat on a table, will be a trapezoidal patch of a certain colour and texture rising vertically in this flattened field. (Nichols 1981, 12). This process of bracketing perception will be more familiar to those who draw or paint who are used to converting three dimensions into two. Key differences between 'bracketed' perception and everyday perception may be summarized as follows (Nichols 1981, 13, 20): Bracketed Perception Normal Perception A bounded visual space, oval, approximately 180° laterally, 150° vertically Unbounded visual space Clarity of focus at only one point with a gradient of increasing vagueness toward the margin (clarity of focus corresponds to the space whose light falls upon the fovea) Clarity of focus throughout Parallel lines appear to converge: the lateral sides of a rectangular surface extending away from the viewer appear to converge Parallel lines extend without converging: the sides of a rectangular surface extending away from the viewer remain parallel If the head is moved, the shapes of objects appear to be deformed If the head is moved, shapes remain constant The visual space appears to lack depth Visual space is never wholly depthless A world of patterns and sensation, of surfaces, edges and gradients A world of familiar objects and meaning Class assignment (group work, done orally): In the following illustrations the idea of 'bracketed' (2-d) perception is exploited. Sometimes it is mixed with normal (3-d) perception. Describe the effect of such "experiments" on the viewer. Do you think it requires a special code convention? Can you see any point in these "experiments"?