9319103 IVRY Theories of object recognition in psychology, physiology, and even computer science have concerned themselves with feature analysis, where features may be line segments, colors, spatial frequencies, etc. According to these theories, recognizing an object involves detecting the features of that object. For example, the features round, shiny, and red might signal an apple. Recently, however, Treisman and her colleagues have pointed out that correct feature registration is not sufficient for veridical object recognition. When many different objects are present, as they are in most natural scenes, observers must not only correctly register the features, but also correctly bind the features into separate objects. Treisman and other have shown that under conditions of a brief exposure, observers will report "illusory conjunctions," or precepts in which they correctly identify the visual features, but combine them incorrectly. For example, an individual briefly presented a red X and a green O would perceive the X as green in some laboratory conditions on up to 30% of the trials. In most circumstances, our visual systems combine features of objects seemingly without error or effort, making the process of feature integration difficult to study. By studying errors in this feature binding process under laboratory conditions (i.e., illusory conjunctions), we can test different theories of feature integration. Unfortunately, the study of feature binding has been hampered for three reasons. First, most theories have been specified in a vague or informal manner. Second, theories have not been formulated in a format that allows a direct test between them. Finally, there has been considerable disagreement on how to measure illusory conjunctions. Many of the widely used methods of measuring feature binding from the occurrence of illusory conjunctions confound feature registration with feature binding. Preliminary research has led to the development of a mathematical model that add resses the above three issues, as well as to the development of a new theory of feature binding, based on probabilistic multidimensional modeling and on the psychophysics of location perception. The 15 experiments to be performed fall into four categories: (1) The formal theory will be tested by varying stimulus values (e.g., color of items) systematically and seeing how they affect parameters of the mathematical model, adjusting the model if necessary. (2) Cognitive variables such as attention will be varied and the effect of these variables on feature integration estimated separately. (3) Different theories of feature binding will be compared directly. (4) The analytic method and formal analysis will be extended to new experimental paradigms, in order to make it as useful as possible to other investigators. ***
