scholarly journals Apparent motion from outside the visual field: Retinotopic cortices may register extraretinal locations

2010 ◽  
Vol 9 (8) ◽  
pp. 694-694
Author(s):  
M. Szinte ◽  
P. Cavanagh
Keyword(s):  
Visual Field ◽  
Apparent Motion

Peripheral Apparent Motion as a Function of Location, Contrast, and Direction of Stimulus Motion

1989 ◽  
Vol 68 (1) ◽  
pp. 33-34 ◽  
Author(s):  
Woodrow Barfield ◽  
Conrad Kraft ◽  
Ali Piyarali
Keyword(s):  
Visual Field ◽  
Apparent Motion ◽  
Stimulus Location ◽  
Peripheral Visual Field ◽  
Stimulus Contrast ◽  
Stimulus Motion ◽  
Independent Variables ◽  
Main Effect

This study investigated the perception of the direction of peripheral apparent motion as a function of stimulus location in the peripheral visual field, stimulus contrast, and the direction of the apparent motion. Results indicated that each of these independent variables was significant as a main effect while the interactions were not.

Measurements of the Relative Tilt of Corresponding Vertical and Horizontal Meridians in the Two Eyes as a Function of Elevation and Eccentricity in the Visual Field

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 226-226 ◽  
Author(s):  
T Ledgeway ◽  
B J Rogers
Keyword(s):  
Visual Field ◽  
Apparent Motion ◽  
Similar Amount ◽  
Optical Instrument ◽  
Orientation Change ◽  
Orientation Difference ◽  
Apparent Orientation

Helmholtz first reported that when the horizontal meridians of the two eyes are aligned, the vertical meridians of the two eyes are tilted outwards (with respect to each other) by approximately 2°. We adapted Nakayama's technique (1977 Proceedings of the Society of Photo-Optical Instrument Engineers120 2 – 9) using the minimal apparent motion of alternating dichoptic images to measure the relative tilt of corresponding vertical and horizontal meridians located up to 20 deg away from the fovea. Observers were presented with the alternating dichoptic images of a pair of dots or a pair of extended lines which had a relative tilt (binocular orientation difference) of between −5° and +5°. The images were alternated at a rate of 0.2 Hz. Observers were asked to select the pair of images which produced the smallest amount of apparent orientation change. The vergence angle of the binocularly visible fixation point was varied between 28 cm and infinity. On the assumption that minimal apparent motion is a valid indicator of binocular correspondence, the corresponding vertical meridians of the two eyes remained offset by around 2 deg even when they were located 20 deg eccentrically. The corresponding horizontal meridians remained approximately aligned even when they were elevated by up to 20 deg. Corresponding horizontal meridians were altered when the vergence angle was changed but corresponding vertical meridians were unaffected for most individuals. With the eyes held in an elevated position, both vertical and horizontal meridians were altered by a similar amount when the vergence angle was altered, indicating a change in cyclovergence.

Asymmetry of the human visual field in magnetic response to apparent motion

2000 ◽  
Vol 865 (2) ◽  
pp. 221-226 ◽  
Author(s):  
Tomoyuki Naito ◽  
Yoshiki Kaneoke ◽  
Naoyuki Osaka ◽  
Ryusuke Kakigi
Keyword(s):  
Visual Field ◽  
Apparent Motion ◽  
Magnetic Response

On the Filling in of the Visual Blind Spot: Some Rules of Thumb

Perception ◽  
1995 ◽  
Vol 24 (7) ◽  
pp. 827-840 ◽  
Author(s):  
Frank H Durgin ◽  
Srimant P Tripathy ◽  
Dennis M Levi
Keyword(s):  
Optic Nerve ◽  
Visual Field ◽  
Apparent Motion ◽  
Surface Segregation ◽  
Blind Spot ◽  
Perceptual Processing ◽  
Occluded Objects ◽  
Rules Of Thumb ◽  
Early Filling ◽  
Blind Spots

In monocular viewing there is a region in the peripheral visual field that is blind owing to the absence of photoreceptors at the site where the optic nerve exits the eye. This region, like certain other blind spots, nonetheless appears filled in. Several novel demonstrations of filling in at the blind spot have recently been reported. Here the implications of many of these effects are critically reevaluated. Specifically, it is argued that many blind-spot phenomena taken to support early filling in (eg pop out and alteration in apparent motion) are actually consistent with the thesis that the visual blind spot is treated by early perceptual processing as a region of reduced or absent information. In support of this, it is shown that many perceptual effects observed in blind-spot completion are similar in detail to the amodally perceived completion of partly occluded objects viewed somewhat peripherally. The goals were to point out striking similarities between blind-spot completion and the amodal completion of occluded parts of surfaces, and to provide a common theoretical framework for understanding these phenomena in the context of surface segregation and perceptual interpolation.

scholarly journals Are there separate ON and OFF channels in fly motion vision?

1992 ◽  
Vol 8 (2) ◽  
pp. 151-164 ◽  
Author(s):  
Martin Egelhaaf ◽  
Alexander Borst
Keyword(s):  
Visual Field ◽  
Apparent Motion ◽  
Motion Detection ◽  
Visual Information ◽  
Detection System ◽  
Time Interval ◽  
Motion Vision ◽  
Response Component ◽  
Retinal Input ◽  
Motion Detection System

AbstractVisual information is processed in a series of subsequent steps. The performance of each of these steps depends not only on the computations it performs itself but also on the representation of the visual surround on which it operates. Here we investigate the consequences of signal preprocessing for the performance of the motion-detection system of the fly. In particular, we analyze whether the retinal input signals are rectified and segregate into separate ON and OFF channels, which then feed independent parallel motion-detection pathways. We recorded the activity of an identified directionally selective interneuron (HI-cell) in response to apparent motion stimuli, i.e. sequential brightness changes at two neighboring locations in the visual field, as well as to brightness changes at only a single location. For apparent motion stimuli, the motion-dependent response component was determined by subtracting from the overall response the responses to the individual stimulus components when presented alone. The following conclusions could be derived: (1) Apparent motion consisting of a sequence of increased or decreased brightness at two locations in the visual field have the same optimum interstimulus time interval (Fig. 3). (2) Sequences of brightness steps of like polarity (either increments or decrements) elicit positive and negative motion-dependent response components when mimicking motion in the cell's preferred and null direction, respectively. The motion-dependent response components are inverted in sign when the brightness steps of a stimulus sequence have a different polarity (Fig. 7). (3) The responses to the beginning and the end of a brightness pulse depend on the pulse duration. For pulse durations of less than 2 s, both events interact with each other (Fig. 9). All of these results do not provide any indication that the fly processes motion information in independent ON and OFF motion detectors. Brightness changes of both signs are rather represented at the input of the same movement detectors, and interactions between signals resulting from both brightness increments and decrements take their sign into account. This type of preprocessing of the retinal input is argued to render a motion-detection system particularly robust against noise.

Apparent Motion of Subjective Surfaces

Perception ◽  
1985 ◽  
Vol 14 (2) ◽  
pp. 127-134 ◽  
Author(s):  
Vilayanur S Ramachandran
Keyword(s):  
Visual Field ◽  
Motion Capture ◽  
Apparent Motion ◽  
Regular Matrix ◽  
Illusory Contours ◽  
Salient Features ◽  
Subjective Surfaces

Apparent motion of an illusory surface was produced by presenting two spatially separated illusory squares in an appropriately timed sequence. Control experiments showed that the effect arose from the illusory contours themselves and not from motion of the cut sectors on the discs. When a template of this movie was superimposed on ‘wallpaper’ composed of a regular matrix of spots, the spots appeared to move with the illusory surface even though they were physically stationary. This effect (‘motion capture’) suggests that the motion of certain salient features in the visual field gets spontaneously attributed to even static elements in the vicinity.

Effects of Visual-Field Inversions on the Reverse-Perspective Illusion

Perception ◽  
10.1068/p3336 ◽  
2002 ◽  
Vol 31 (9) ◽  
pp. 1147-1151 ◽  
Author(s):  
Norman D Cook ◽  
Takefumi Hayashi ◽  
Toshihiko Amemiya ◽  
Kimihiro Suzuki ◽  
Lorenz Leumann
Keyword(s):  
Visual Field ◽  
Apparent Motion ◽  
Visual Information ◽  
Motion Parallax ◽  
Body Movement ◽  
Implicit Knowledge ◽  
Linear Perspective ◽  
Illusory Motion ◽  
Depth Cues

The ‘reverse-perspective’ illusion entails the apparent motion of a stationary scene painted in relief and containing misleading depth cues. We have found that, using prism goggles to induce horizontal or vertical visual-field reversals, the illusory motion is greatly reduced or eliminated in the direction for which the goggles reverse the visual field. We argue that the illusion is a consequence of the observer's inability to reconcile changes in visual information due to body movement with implicit knowledge concerning anticipated changes. As such, the reverse-perspective illusion may prove to be useful in the study of the integration of linear perspective and motion parallax information.

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