Position shifts following crowded second-order motion adaptation reveal processing of local and global motion without awareness. 2007

Thomas D Harp, and David W Bressler, and David Whitney
Department of Psychology, University of California, Davis, CA, USA.

Adaptation to first-order (luminance defined) motion produces not only a motion aftereffect but also a position aftereffect, in which a target pattern's perceived location is shifted opposite the direction of adaptation. These aftereffects can occur passively (when the direction of motion adaptation cannot be detected) and remotely (when the target is not at the site of adaptation). Although second-order (contrast defined) motion produces these aftereffects, it is unclear whether they can occur passively or remotely. To address these questions, we conducted two experiments. In the first, we used crowding to remove a local adapter's second-order motion from awareness and still found a significant position aftereffect. In the second experiment, we found that the direction of motion in one region of a crowded array could produce a position aftereffect in an unadapted, spatially separated region of the crowded array. The results suggest that second-order motion influences perceived position over a large spatial range even without awareness.

UI MeSH Term Description Entries
D009039 Motion Perception The real or apparent movement of objects through the visual field. Movement Perception,Perception, Motion,Perception, Movement
D010470 Perceptual Masking The interference of one perceptual stimulus with another causing a decrease or lessening in perceptual effectiveness. Masking, Perceptual,Maskings, Perceptual,Perceptual Maskings
D005366 Figural Aftereffect A perceptual phenomenon used by Gestalt psychologists to demonstrate that events in one part of the perceptual field may affect perception in another part. Aftereffect, Figural,Aftereffects, Figural,Figural Aftereffects
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000222 Adaptation, Physiological The non-genetic biological changes of an organism in response to challenges in its ENVIRONMENT. Adaptation, Physiologic,Adaptations, Physiologic,Adaptations, Physiological,Adaptive Plasticity,Phenotypic Plasticity,Physiological Adaptation,Physiologic Adaptation,Physiologic Adaptations,Physiological Adaptations,Plasticity, Adaptive,Plasticity, Phenotypic
D001364 Awareness The act of "taking account" of an object or state of affairs. It does not imply assessment of, nor attention to the qualities or nature of the object. Situation Awareness,Situational Awareness,Awareness, Situation,Awareness, Situational,Awarenesses,Awarenesses, Situation,Awarenesses, Situational,Situation Awarenesses,Situational Awarenesses
D013028 Space Perception The awareness of the spatial properties of objects; includes physical space. Perception, Space,Perceptions, Space,Space Perceptions
D015350 Contrast Sensitivity The ability to detect sharp boundaries (stimuli) and to detect slight changes in luminance at regions without distinct contours. Psychophysical measurements of this visual function are used to evaluate VISUAL ACUITY and to detect eye disease. Visual Contrast Sensitivity,Sensitivity, Contrast,Sensitivity, Visual Contrast

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