The CRIP effect: How a pattern in central vision interferes with perception of a pattern in the periphery.

Our percept of the world is the result of interactions between central and peripheral vision. They can be facilitatory, because central vision is informative about what is in the periphery, or detrimental, such as when shape elements are pooled. We introduce a novel phenomenon, in which elements in the central region impair perception in the periphery (central region interference with periphery [CRIP]). We showed participants a squared grid containing small lines (vertical or diagonal) or crosses in the central region and diagonal lines in the periphery. The regions were divided by a gap that varied in size and position. Participants reported the orientation of the diagonal lines in the periphery (/ or \). The central pattern caused interference and hindered discrimination. For a fixed eccentricity of the peripheral elements, the smaller the gap the larger the impairment. The effect was only present when the central and peripheral lines had a shared orientation (i.e., diagonal), suggesting that similarity plays a role. Surprisingly, performance was worse if central and peripheral lines had the same orientation. We conclude that people do not rely on extrapolation when perceiving elements in the periphery and that iso-orientation may cause greater interference.