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Inter-element orientation and distance influence the duration of persistent contour integration.

Strother L, Alferov D - Front Psychol (2014)

Bottom Line: Crucially, these contours remained visible for up to a few seconds following onset, but eventually disappeared due to the camouflaging effects of surrounding background line segments.The stimulus-related effects reported here parallel similar results from contour detection studies, and complement previous reported top-down influences on contour persistence (Strother et al., 2011).We propose that persistent contour visibility reflects the sustained activity of recurrent processing loops within and between visual cortical areas involved in contour integration and other important stages of visual object recognition.

View Article: PubMed Central - PubMed

Affiliation: Brain and Mind Institute, University of Western Ontario London, ON, Canada ; Cognitive and Brain Sciences Program, Department of Psychology, University of Nevada Reno Reno, NV, USA.

ABSTRACT
Contour integration is a fundamental form of perceptual organization. We introduce a new method of studying the mechanisms responsible for contour integration. This method capitalizes on the perceptual persistence of contours under conditions of impending camouflage. Observers viewed arrays of randomly arranged line segments upon which circular contours comprised of similar line segments were superimposed via abrupt onset. Crucially, these contours remained visible for up to a few seconds following onset, but eventually disappeared due to the camouflaging effects of surrounding background line segments. Our main finding was that the duration of contour visibility depended on the distance and degree of co-alignment between adjacent contour segments such that relatively dense smooth contours persisted longest. The stimulus-related effects reported here parallel similar results from contour detection studies, and complement previous reported top-down influences on contour persistence (Strother et al., 2011). We propose that persistent contour visibility reflects the sustained activity of recurrent processing loops within and between visual cortical areas involved in contour integration and other important stages of visual object recognition.

No MeSH data available.


Related in: MedlinePlus

Results from Experiments 3a and 3b. In (A), contour persistence (mean log RT) was greater for smooth circles and semi-circles as compared to jagged circles and semi-circles. Error bars are 95% confidence intervals. In (B), contour persistence was greater for smooth versus jagged contours, even when trials with eye movements that deviated beyond 1.5° from fixation were omitted (the latter are shown in the dashed box with the eye symbol above).
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Figure 5: Results from Experiments 3a and 3b. In (A), contour persistence (mean log RT) was greater for smooth circles and semi-circles as compared to jagged circles and semi-circles. Error bars are 95% confidence intervals. In (B), contour persistence was greater for smooth versus jagged contours, even when trials with eye movements that deviated beyond 1.5° from fixation were omitted (the latter are shown in the dashed box with the eye symbol above).

Mentions: This experiment was a partial replication of Experiment 2 (same observers) in which we sought to replicate the smooth > jagged log RT result for non-closed contours (semi-circles). Figure 5A shows mean log RTs corresponding to circles (solid bars) and semi-circles (dots with error bars) obtained in Experiment 3a. The same smooth > jagged log RT trend was observed in all three cases. A repeated measures ANOVA showed a main effect of inter-element alignment [smooth > jagged; F(1,5) = 7.7, p < 0.01]; a main effect of closure (with circles persisting longer than semi-circles) approached significance [F(1,5 = 2.9, p = 0.09], and there were no significant interactions. This means that the smooth > jagged effect shown in Figures 3 and 4 is not limited to closed contours.


Inter-element orientation and distance influence the duration of persistent contour integration.

Strother L, Alferov D - Front Psychol (2014)

Results from Experiments 3a and 3b. In (A), contour persistence (mean log RT) was greater for smooth circles and semi-circles as compared to jagged circles and semi-circles. Error bars are 95% confidence intervals. In (B), contour persistence was greater for smooth versus jagged contours, even when trials with eye movements that deviated beyond 1.5° from fixation were omitted (the latter are shown in the dashed box with the eye symbol above).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4222348&req=5

Figure 5: Results from Experiments 3a and 3b. In (A), contour persistence (mean log RT) was greater for smooth circles and semi-circles as compared to jagged circles and semi-circles. Error bars are 95% confidence intervals. In (B), contour persistence was greater for smooth versus jagged contours, even when trials with eye movements that deviated beyond 1.5° from fixation were omitted (the latter are shown in the dashed box with the eye symbol above).
Mentions: This experiment was a partial replication of Experiment 2 (same observers) in which we sought to replicate the smooth > jagged log RT result for non-closed contours (semi-circles). Figure 5A shows mean log RTs corresponding to circles (solid bars) and semi-circles (dots with error bars) obtained in Experiment 3a. The same smooth > jagged log RT trend was observed in all three cases. A repeated measures ANOVA showed a main effect of inter-element alignment [smooth > jagged; F(1,5) = 7.7, p < 0.01]; a main effect of closure (with circles persisting longer than semi-circles) approached significance [F(1,5 = 2.9, p = 0.09], and there were no significant interactions. This means that the smooth > jagged effect shown in Figures 3 and 4 is not limited to closed contours.

Bottom Line: Crucially, these contours remained visible for up to a few seconds following onset, but eventually disappeared due to the camouflaging effects of surrounding background line segments.The stimulus-related effects reported here parallel similar results from contour detection studies, and complement previous reported top-down influences on contour persistence (Strother et al., 2011).We propose that persistent contour visibility reflects the sustained activity of recurrent processing loops within and between visual cortical areas involved in contour integration and other important stages of visual object recognition.

View Article: PubMed Central - PubMed

Affiliation: Brain and Mind Institute, University of Western Ontario London, ON, Canada ; Cognitive and Brain Sciences Program, Department of Psychology, University of Nevada Reno Reno, NV, USA.

ABSTRACT
Contour integration is a fundamental form of perceptual organization. We introduce a new method of studying the mechanisms responsible for contour integration. This method capitalizes on the perceptual persistence of contours under conditions of impending camouflage. Observers viewed arrays of randomly arranged line segments upon which circular contours comprised of similar line segments were superimposed via abrupt onset. Crucially, these contours remained visible for up to a few seconds following onset, but eventually disappeared due to the camouflaging effects of surrounding background line segments. Our main finding was that the duration of contour visibility depended on the distance and degree of co-alignment between adjacent contour segments such that relatively dense smooth contours persisted longest. The stimulus-related effects reported here parallel similar results from contour detection studies, and complement previous reported top-down influences on contour persistence (Strother et al., 2011). We propose that persistent contour visibility reflects the sustained activity of recurrent processing loops within and between visual cortical areas involved in contour integration and other important stages of visual object recognition.

No MeSH data available.


Related in: MedlinePlus