The role of edges and line-ends in illusory contour formation

Lesher, Gregory W.; Mingolla, Ennio

doi:10.1016/0042-6989(93)90104-5

Cited by 91 publications

(75 citation statements)

References 50 publications

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“…Again, the individual result of 6 subjects has the same trend: CH (F(2,8) These results show that under all types of stimuli (Still, ExpansB, ExpansI and ExpansF), the perceived strength will increase with increasing pacmen size and decreasing inter-pacmen gap. Again it not only provides further evidence for previous studies [22,23] , but also proves our experimental method to be reliable. seemed to perceive weaker illusory contours in ExpansB than in Still.…”

Section: Resultssupporting

confidence: 68%

Perception of illusory contours enhanced in motion

Ni¹

2003

Sci China Ser C

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Investigation on illusory contours is important for understanding the mechanisms underlying the object recognition of human visual system. Numerous researches have shown that illusory contours formed in motion and stereopsis are generated by the unmatched features. Here we conduct three psychophysical experiments to test if Kanizsa illusory contours are also caused by unmatched information. Different types of motion (including horizontal translation, radial expanding and shrinking) are utilized in the experiments. The results show that no matter under what kind of motion, when figures or background move separately illusory contours are perceived stronger, and there is no significant difference between the perceived strength in these two types of motion. However, no such enhancement of perceived strength is found when figures and background move together. It is found that the strengthened unmatched features generate the enhancement effect of illusory contour perception in motion. Thus the results suggest that the process of unmatched information in visual system is a critical step in the formation of illusory contours.

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Section: Resultssupporting

confidence: 68%

Perception of illusory contours enhanced in motion

Ni¹

2003

Sci China Ser C

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“…These data suggest the primary role of inducer collinearity and edges alignment in the completion of illusory boundaries [21] at relatively early stages of visual processing.…”

Section: Discussionmentioning

confidence: 82%

“…Subjective figures are often perceived as brighter (or darker, depending on background colour) than the surrounding surface [15,16,33] and brightness seems to vary as a function of contour clarity or sharpness of illusory edges [21]. Other studies showed that the apparent increase in brightness of subjective figures and boundary contours completion are different phenomena, depending on several factors [7,24,29].…”

Section: Introductionmentioning

confidence: 99%

Electrophysiological indexes of illusory contours perception in humans

Proverbio

Zani

2002

Neuropsychologia

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The present study investigated brain mechanisms underlying the perception of illusory contours, using recordings of event-related potentials of the brain (ERPs) in right-handed individuals. Forty different stimuli were presented randomly 1600 times in foveal vision; twenty of them produced the perception of illusory contours of a Kanizsa square, the remaining were obtained rotating outwards the inducers and they did not produce any illusory percept. Half of them had white inducers on a black background and vice versa; half of them were symmetrical and the other half asymmetrical. In lateral occipital areas illusory percepts produced larger evoked responses starting as early as 145 ms post-stimulus with the N1 peak. ERP data did not provide evidence of right-sided lateralisation of the processes underlying illusory contours formation at sensory level, as suggested by some neuroimaging and neuropsychological studies. The two cerebral hemispheres were differently activated while the subjective patterns formation progressed through neural processing stages. Indeed, brain response to illusory contours was more pronounced in the left occipital area at N2 component level (about 250 ms post-stimulus) and at right parietal sites at the latency of P300 component. Both background luminance and stimulus symmetry interacted with illusory boundaries formation. Present results confirm the hypothesis that the integration of contours arises at early stages of visual processing and highlight the primary role of edges continuity and boundary alignment in illusory contours perception.

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“…It has been proposed that illusory contours that are induced by edges and those induced by the ends of lines may be mediated by similar mechanisms (see Lesher and Mingolla 1993;Lesher 1995, for reviews). For example, the effect of contrast polarity (Prazdny 1983;Hershberger and Stallard 1984), the effect of spatial factors on the strength of the illusion (Lesher and Mingolla 1993;Salvano-Pardieu 2000) and their neural mechanisms (Peterhans et al 1986;Peterhans and von der Heydt 1989;Heitger et al 1992;Peterhans and Heitger 2001) seem to be similar.…”

Section: Discussionmentioning

confidence: 99%

Can Subthreshold Summation Be Observed with the Ehrenstein Illusion?

Salvano-Pardieu

Wink

Taliercio³

et al. 2006

Perception

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Subthreshold summation between physical target lines and illusory contours induced by edges such as those produced in the Kanizsa illusion has been reported in previous studies. Here, we investigated the ability of line-induced illusory contours, using Ehrenstein figures, to produce similar subthreshold summation. In the first experiment, three stimulus conditions were presented. The target line was superimposed on the illusory contour of a four-arm Ehrenstein figure, or the target was presented between two dots (which replaced the arms of the Ehrenstein figure), or the target was presented on an otherwise blank screen (control). Detection of the target line was significantly worse when presented on the illusory contour (on the Ehrenstein figure) than when presented between two dots. This result was consistent for both curved and straight target lines, as well as for a 100 ms presentation duration and unlimited presentation duration. Performance was worst in the control condition. The results for the three stimulus conditions were replicated in a second experiment in which an eight-arm Ehrenstein figure was used to produce a stronger and less ambiguous illusory contour. In the third experiment, the target was either superimposed on the illusory contour, or was located across the central gap (illusory surface) of the Ehrenstein figure, collinear with two arms of the figure. As in the first two experiments, the target was either presented on the Ehrenstein figure, or between dots, or on a blank screen. Detection was better in the dot condition than in the Ehrenstein condition, regardless of whether the target was presented on the illusory contour or collinear with the arms of the Ehrenstein figure. These three experiments demonstrate the ability of reduced spatial uncertainty to facilitate the detection of a target line, but do not provide any evidence for subthreshold summation between a physical target line and the illusory contours produced by an Ehrenstein figure. The incongruence of these results with previous findings on Kanizsa figures is discussed.

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The role of edges and line-ends in illusory contour formation

Cited by 91 publications

References 50 publications

Perception of illusory contours enhanced in motion

Perception of illusory contours enhanced in motion

Electrophysiological indexes of illusory contours perception in humans

Can Subthreshold Summation Be Observed with the Ehrenstein Illusion?

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