Cognitive Contours

  title={Cognitive Contours},
  author={RICHARD L. Gregory},
IT is surprisingly easy to devise simple line figures which evoke marked illusory contours. Unlike the well known brightness contrast effects, these illusory contours can occur in regions far removed from regions of physical intensity difference; and they can be orientated at any angle to physically present contours. Fig. 1 is the figure described by Kanizsa1. An illusory triangle is observed whose apices are determined by the blank sectors of the three disks. The “created” object appears to… 

Illusory Contours Can Arise in Dot Figures

The kind of contrast explanation required for these figures would be one in which individual dots create small contrast effects which are only manifest in perception when the effects are grouped together, by Gestalt form indicators, overlap cues, or the like.

A Figure-Density Hypothesis and Illusory Contour Brightness

Rather than explain subjective brightness effects as offshoots of figural processes, it may be better to begin with concepts of local brightness effects induced by the display, which are made perceptually effective when grouped by the eye.

The Nonequivalence of Abrupt and Diffuse Illusory Contours

A distinction is drawn between diffuse regions of apparent brightness and illusory, but abrupt, brightness gradients and it is suggested that diffuse contours may be attributable to peripheral mechanisms while sharp contours are central or cognitive in origin.

Illusory contours and stereo depth

It is suggested that nearer masking objects are perceptually postulated to “account” for gaps when these are unlikely, and when stereoscopic depth information incompatible with this “perceptual hypothesis” is presented, the illusory contours are reduced in intensity or disappear.

Fusion and Rivalry of Illusory Contours

The general question is raised: “Are visual contours given directly from striate-cortex feature-detector activity?‘’ Phenomena of ‘subjective’ or ‘cognitive’ contours are examined to challenge this

Illusory contours from inducers defined solely by spatiotemporal correlation

  • K.
  • Geology
  • 2010
Vivid and perceptually salient subjective contours are perceived when inducing (two-dimensional) objects that move and change form so as to "simulate" the presence of an occluding shape are defined

Illusory contours and spatial judgment

The errors in aligning a dot with an illusory contour seem to be related to the asymmetrical shape of the single objects, which are able to induce an illused contour, as well as figure-ground segregation.

Stimulus determinants of brightness and distinctness of subjective contours

It was found that apparent brightness is influenced more by number of inducing elements, whereas apparent sharpness increases more with inducing element width, and stimulus configuration may influence brightness and sharpness differentially.

The Determinants of Illusory-Contour Perception

Experimental results suggest that different processes may assume a primary role in the perception of illusory contours depending upon the type of inducing area and the configuration, and indicate that no single theory can explain the perception.