Synthesizing Complex Perceptions: I. Concepts of Visual Feature Associations Based on Neural Synchronization and Related Experimental Results in the Visual Cortex

Abstract

Stimuli composed of coherent features are integrated by our sensory systems into perceptual entities. We can perceive, for example, a visual object as a perceptual whole even if various aspects of the object are occluded, obscured by the background, or are not present at all. The visual system can easily detect coherences in an object’s local stimulus features, and is able to link, intensify and isolate them. Such capabilities generally require minimal feature contrast against background and the object has to obey certain rules of Gestalt properties. It is, for example, easy for us to recognize the triangles in Fig. 1 even though they are presented only in parts. It has been shown by psychophysical experiments (e. g., Field et al. 1993) that such types of feature association do not require prerational knowledge because they occur with arbitrary shapes of object contours (in psychophysics such associations are called pre-attentive). Consequently, the underlying neural mechanisms supporting perceptual grouping, mutual facilitation, and figure/ground separation have also to act prerationally and should be highly flexible in order to cope with the immense variety of local feature combinations in natural scenes.