Kinetic Occlusion by Apparent Movement

Perception ◽  
1985 ◽  
Vol 14 (2) ◽  
pp. 145-149 ◽  
Author(s):  
Stuart M Anstis ◽  
Vilayanur S Ramachandran
Keyword(s):  
Visual System ◽  
Apparent Movement ◽  
Large Triangle

A small square and a large triangle below it were presented in the first frame. These were switched off and replaced by a triangle alone in the second frame, shifted horizontally and upwards. The triangle appeared to move obliquely, as expected, but most observers also saw the square moving horizontally and hiding behind the triangle, although there was no stimulus corresponding to it in the second frame. The visual system invokes the occlusion ‘hypothesis’ in order to explain the otherwise mysterious disappearance of the square. The experiment suggests that apparently intelligent solutions can be rapidly computed by the visual system.

Temporal Characteristics in Apparent Movement: Omega Movement vs. PHI Movement

1973 ◽  
Vol 25 (2) ◽  
pp. 182-192 ◽  
Author(s):  
C. William Tyler
Keyword(s):  
Visual System ◽  
Interstimulus Interval ◽  
Apparent Movement ◽  
Displacement Amplitude ◽  
Vertical Line ◽  
Line Stimulus ◽  
Temporal Characteristics ◽  
Time Movement

A vertical line stimulus was presented alternately at two positions on an oscillo scope face, with no interstimulus interval. Observation of this stimulus produced haphazard alternation between a number of movement percepts, which were divided into four categories: phi, omega and partial movement, and no movement. Attention to one category did not increase the proportion of time movement in that category it was reported. Proportion of time reported for each category varied differentially as a function of alternation frequency. Upper and lower displacement amplitude limits were measured as a function of frequency for phi and omega movement. Both limits for omega movement differed from those for phi movement. The results imply that phi and omega movement involve separate processing stages in the visual system.

Evidence for Separate Movement and Form Channels in the Human Visual System

Perception ◽  
1974 ◽  
Vol 3 (1) ◽  
pp. 87-96 ◽  
Author(s):  
J P Frisby ◽  
J L Clatworthy
Keyword(s):  
Visual System ◽  
Human Visual System ◽  
Apparent Movement ◽  
Selective Adaptation ◽  
Movement Direction ◽  
Adaptation Stimulus ◽  
Real Movement ◽  
Moving Stimulus ◽  
Adaptation Effects

Two experiments are described which investigated the possibility that the directional and form aspects of a moving stimulus are coded in separate neural locations. The experiments employed an adaptation paradigm in which sensitivities to grids in optimal apparent movement were measured following an adaptation exposure to a grid in real movement. The postadaptation grids possessed varying degrees of similarity to the adaptation stimulus: they could either have a similar orientation and a similar movement direction, or they could differ on just one of these dimensions, or they could differ on both of these dimensions. Selective adaptation effects were observed which were interpreted as supporting the hypothesis that different form and movement channels exist in the human visual system.

Author response for "The brain of the African wild dog. IV . The visual system"

2020 ◽  
Author(s):  
Samson Chengetanai ◽  
Adhil Bhagwandin ◽  
Mads F. Bertelsen ◽  
Therese Hård ◽  
Patrick R. Hof ◽  
...  
Keyword(s):  
Visual System ◽  
Author Response ◽  
African Wild Dog ◽  
Wild Dog ◽  
The Brain

Digital differential hysteresis iimage processing displays what the microscope acquires but the eye can't see

1995 ◽  
Vol 53 ◽  
pp. 642-643
Author(s):  
Klaus-Ruediger Peters
Keyword(s):  
Image Processing ◽  
Visual System ◽  
High Precision ◽  
Image Data ◽  
Processing Technology ◽  
Output Data ◽  
Contrast Resolution ◽  
Pixel Intensity ◽  
Data Reading ◽  
Hysteresis Properties

Differential hysteresis processing is a new image processing technology that provides a tool for the display of image data information at any level of differential contrast resolution. This includes the maximum contrast resolution of the acquisition system which may be 1,000-times higher than that of the visual system (16 bit versus 6 bit). All microscopes acquire high precision contrasts at a level of <0.01-25% of the acquisition range in 16-bit - 8-bit data, but these contrasts are mostly invisible or only partially visible even in conventionally enhanced images. The processing principle of the differential hysteresis tool is based on hysteresis properties of intensity variations within an image.Differential hysteresis image processing moves a cursor of selected intensity range (hysteresis range) along lines through the image data reading each successive pixel intensity. The midpoint of the cursor provides the output data. If the intensity value of the following pixel falls outside of the actual cursor endpoint values, then the cursor follows the data either with its top or with its bottom, but if the pixels' intensity value falls within the cursor range, then the cursor maintains its intensity value.

Newborn's Preference for Faces

1996 ◽  
Vol 1 (3) ◽  
pp. 200-205 ◽  
Author(s):  
Carlo Umiltà ◽  
Francesca Simion ◽  
Eloisa Valenza
Keyword(s):  
Visual System ◽  
Structural Properties ◽  
Sensory Properties ◽  
Human Face ◽  
System Experiment ◽  
Face Experiment

Four experiments were aimed at elucidating some aspects of the preference for facelike patterns in newborns. Experiment 1 showed a preference for a stimulus whose components were located in the correct arrangement for a human face. Experiment 2 showed a preference for stimuli that had optimal sensory properties for the newborn visual system. Experiment 3 showed that babies directed their attention to a facelike pattern even when it was presented simultaneously with a non-facelike stimulus with optimal sensory properties. Experiment 4 showed the preference for facelike patterns in the temporal hemifield but not in the nasal hemifield. It was concluded that newborns' preference for facelike patterns reflects the activity of a subcortical system which is sensitive to the structural properties of the stimulus.

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