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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

The top three panels illustrate the contour fading paradigm. When a circle comprised of discrete elements appears (top left panel) against a background of similar elements it remains visible (top middle panel) for up to several seconds but eventually becomes camouflaged (top right panel), and it is perceived to have disappeared even though the circle is still physically present. Note that the circle is darkened in the left two panels to illustrate its perceptibility rather than an actual difference in luminance between circle elements and background elements. The three inter-element alignment conditions used in Experiment 1 are also shown (bottom).
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Figure 1: The top three panels illustrate the contour fading paradigm. When a circle comprised of discrete elements appears (top left panel) against a background of similar elements it remains visible (top middle panel) for up to several seconds but eventually becomes camouflaged (top right panel), and it is perceived to have disappeared even though the circle is still physically present. Note that the circle is darkened in the left two panels to illustrate its perceptibility rather than an actual difference in luminance between circle elements and background elements. The three inter-element alignment conditions used in Experiment 1 are also shown (bottom).

Mentions: All experiments employed stimuli comprised of short line segments (Figure 12). Trials began with the appearance of a ‘background’ array of randomly oriented dark line segments (∼0.3° × 0.03°) positioned randomly (overlap allowed) within a lighter 10° × 10° square aperture on an otherwise dark display. A blue fixation cross (∼0.3° × 0.3°) was always present in the center of the aperture during the experiments. Shortly (2 s) after the appearance of the background array, a circle or semi-circle comprised of line segments identical to those comprising the background appeared against the background and remained until the end of the trial (total trial duration was always 8 s). We used snake circles comprised of co-circular elements (i.e., smooth contours), ladder circles comprised of co-radial (rotated 90° from co-circular), and jagged circles comprised of randomly oriented elements (random orientations were generated trial to trial). The absolute positions of each of the elements along a circle or semi-circle were equivalent across all three stimulus types and conditions.


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

Strother L, Alferov D - Front Psychol (2014)

The top three panels illustrate the contour fading paradigm. When a circle comprised of discrete elements appears (top left panel) against a background of similar elements it remains visible (top middle panel) for up to several seconds but eventually becomes camouflaged (top right panel), and it is perceived to have disappeared even though the circle is still physically present. Note that the circle is darkened in the left two panels to illustrate its perceptibility rather than an actual difference in luminance between circle elements and background elements. The three inter-element alignment conditions used in Experiment 1 are also shown (bottom).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: The top three panels illustrate the contour fading paradigm. When a circle comprised of discrete elements appears (top left panel) against a background of similar elements it remains visible (top middle panel) for up to several seconds but eventually becomes camouflaged (top right panel), and it is perceived to have disappeared even though the circle is still physically present. Note that the circle is darkened in the left two panels to illustrate its perceptibility rather than an actual difference in luminance between circle elements and background elements. The three inter-element alignment conditions used in Experiment 1 are also shown (bottom).
Mentions: All experiments employed stimuli comprised of short line segments (Figure 12). Trials began with the appearance of a ‘background’ array of randomly oriented dark line segments (∼0.3° × 0.03°) positioned randomly (overlap allowed) within a lighter 10° × 10° square aperture on an otherwise dark display. A blue fixation cross (∼0.3° × 0.3°) was always present in the center of the aperture during the experiments. Shortly (2 s) after the appearance of the background array, a circle or semi-circle comprised of line segments identical to those comprising the background appeared against the background and remained until the end of the trial (total trial duration was always 8 s). We used snake circles comprised of co-circular elements (i.e., smooth contours), ladder circles comprised of co-radial (rotated 90° from co-circular), and jagged circles comprised of randomly oriented elements (random orientations were generated trial to trial). The absolute positions of each of the elements along a circle or semi-circle were equivalent across all three stimulus types and conditions.

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