A useful approach to studying the processes that underlie visual cognition is to study the errors that people make. By examining patterns of errors and the conditions that predictably cause them, it is possible to infer the principles that guide visual perception and memory. Two lines of research will test the effects of viewers' general knowledge about the structure of naturalistic scenes on their ability to perceive and remember pictures. One series of experiments will examine a perceptual illusion that occurs during high-speed presentation of pictures (e.g., 9/sec), in which an object from one picture is frequently misperceived as having occurred in the immediately preceding or following display in the sequence. The relationship of the object to the display in which it actually appears, and to those that surround it, will be manipulated such that the object either will or will not conform to the observer's knowledge of real-world scenes. The research will evaluate the effect of such manipulations on frequency of misperception. The other series of experiments will test a memory distortion that occurs when viewers try to remember close-up photographs of objects. Observers tend to recollect seeing information that was not present in the photograph, but is likely to have existed just outside the camera's point of view. This suggests that general scene knowledge is important in understanding pictorial representation and that it alters memory in a predictable and measurable way. This basic research on picture comprehension and memory has implications for visual communications (e.g., video displays, control panel design), particulary under conditions in which errors and brief delays may be crucial to avoid.
