There is No Evidence That Kanizsa-Type Subjective Contours Can Be Detected in Parallel

Abstract

Davis and Driver presented evidence suggesting that Kanizsa-type subjective contours could be detected in a visual search task in a time that is independent of the number of nonsubjective contour distractors. A linking connection was made between these psychophysical data and the physiological data of Peterhans and von der Heydt which showed that cells in primate area V2 respond to subjective contours in the same way that they respond to luminance-defined contours. Here in three experiments it is shown that there was sufficient information in the displays used by Davis and Driver to support parallel search independently of whether subjective contours were present or not. When confounding properties of the stimuli were eliminated search became slow whether or not subjective contours were present in the display. One of the slowest search conditions involved stimuli that were virtually identical to those used in the physiological studies of Peterhans and von der Heydt to which Davis and Driver wish to link their data. It is concluded that while subjective contours may be represented in the responses of very early visual mechanisms (eg in V2) access to these representations is impaired by high-contrast contours used to induce the subjective contours and nonsubjective figure distractors. This persistent control problem continues to confound attempts to show that Kanizsa-type subjective contours can be detected in parallel.

Effects of stimulus synchrony on mechanisms of perceptual organization

“…This seems somewhat counterintuitive considering other findings (i.e, Shipley & Kelman, 1992) that show the "goodness" of Kanizsa-types figures is largely due to the separation between inducer elements. It may be that, in this instance the collinear line segments do not encourage illusory contour formation (see, e.g., Gurnsey, Poirier, & Gascon, 1996) with the result that activity across the prime, although representing the square-arrangement of the synchronous premask elements, may not be considered in the same terms as the "subjective experience" of an illusory Kanizsa square (which is directly supported by perception of the illusory contours). This is plausible considering that observers do not detect the synchronous-premask frame, rendering tenuous an account of priming according to stimulus properties more commonly associated with subjective experience.…”

Orientation-Selective Adaptation to Illusory Contours in Human Visual Cortex

“…Second, the absence of V1 activity in previous studies could be a result of less-sensitive scanner hardware (lower field strength and lesssensitive receiver coils), different data analysis techniques, or a failure to define V1 retinotopically. Third, many of the previous studies used the Kanizsa-type illusory contours, which may be processed differently from the abutting-line gratings used in our study (Gurnsey et al, 1992(Gurnsey et al, , 1996.…”

Closure of salient regions determines search for a collinear target configuration

“…1 Studies in which visual search for illusory figures has been investigated have thus far led to equivocal interpretations with regard to the stage at which illusory figures are completed. Whereas some authors have proposed that search is based on preattentive completion of illusory contours (Davis & Driver, 1994), others have argued that there is no definite evidence to support the idea that Kanizsa-type figures are detected in parallel (Grabowecky & Treisman, 1989;Gurnsey, Poirier, & Gascon, 1996). Follow-up investigations (Conci, Müller, & Elliott, 2007) have shown that surface specifications in distractors influence search for an illusory target figure, whereas contour specifications have little direct effect on target detection.…”