We have recently described an adaptation effect with Glass patterns (Figure 1) in which the organized pattern dissipates with prolonged viewing. This dissipation only occurs for patterns 1A and 1B and not for 1C. The possible explanation for this is that the patterns in 1A and 1B seem to require processing in cortical area V4 for detection whereas those in 1C may be detected by processes earlier in the cortical visual pathways (Wilson et al , 1999). In our Perception article (McGraw, Badcock & Khuu, Perception, 33, pp. 121-125) we undertook to provide examples of stimuli differing in density, area, and contrast in order to show the generality of this effect. Links to those images are provided on the left.

Example Patterns

Reproduction of Figure 1 from McGraw, Badcock & Khuu (2004). The legend there is: 

Four types of Glass pattern structure: (a) a concentric Glass pattern; (b) a radial Glass pattern; (c) a parallel Glass pattern; and (d) a pattern in which the dipoles are randomly oriented and thus do not form a global structure. If fixation is held steadily on the fixation mark at the centre of (a) from a distance of approximately 20 cm, the observer should see the collapse of the concentric global structure after several seconds, and the pattern take on a random appearance [similar to (d)].

Repeating the process for (b) produces a similar result. However, steady fixation of (c) has little impact, and the parallel global structure is markedly less affected.