Publication

Grouping explains contextual modulation in low level vision

Michael Herzog, Bilge Sayim
2008
Conference Papers

Abstract

Performance on a target can be modified by contextual elements. For example, when a Vernier is flanked by two lines, offset discrimination deteriorates compared to an unflanked presentation. This contextual modulation is usually explained by local spatial interactions between the Vernier and the flanks. We have shown that this explanation is inadequate. Instead, we propose that flanks interfere most strongly when they are grouped with the Vernier. In a number of experiments, we have shown that interference between flanks and Vernier can be reduced when the flanks form an independent group and the Vernier stands out. Our experiments show that this ungrouping can be established by differences in features like contrast polarity, colour, and stereoscopic depth, as well as flank grouping by figural properties. For example, Vernier discrimination thresholds are significantly lower when the Vernier is flanked by two cuboids compared to being flanked by two lines which are contained in the cuboids. Our results show that global Gestalt aspects are crucial in contextual modulation

Official source

https://infoscience.epfl.ch/entities/publication/5a44e8ac-b250-4a7e-babc-1de04dda3de3

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Michael Herzog, Bilge Sayim
2008
Conference Papers

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/5a44e8ac-b250-4a7e-babc-1de04dda3de3

About this result

Related concepts (14)

Stereoscopy

Stereoscopy (also called stereoscopics, or stereo imaging) is a technique for creating or enhancing the illusion of depth in an image by means of stereopsis for binocular vision. The word stereoscopy derives . Any stereoscopic image is called a stereogram. Originally, stereogram referred to a pair of stereo images which could be viewed using a stereoscope. Most stereoscopic methods present a pair of two-dimensional images to the viewer. The left image is presented to the left eye and the right image is presented to the right eye.

Stereopsis

Stereopsis () is the component of depth perception retrieved through binocular vision. Stereopsis is not the only contributor to depth perception, but it is a major one. Binocular vision happens because each eye receives a different image because they are in slightly different positions on one's head (left and right eyes). These positional differences are referred to as "horizontal disparities" or, more generally, "binocular disparities". Disparities are processed in the visual cortex of the brain to yield depth perception.

Depth perception

Depth perception is the ability to perceive distance to objects in the world using the visual system and visual perception. It is a major factor in perceiving the world in three dimensions. Depth perception happens primarily due to stereopsis and accommodation of the eye. Depth sensation is the corresponding term for non-human animals, since although it is known that they can sense the distance of an object, it is not known whether they perceive it in the same way that humans do. Depth perception arises from a variety of depth cues.

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