Low-Level Motion Illusions

2017 ◽  
Author(s):  
Stuart Anstis
Keyword(s):  
Visual Motion ◽  
Viewing Distance ◽  
Low Level ◽  
Space And Time ◽  
Smooth Movement ◽  
Perceived Speed

Visual motion stimuli can be defined as changes in luminance over space and time. Both kinds of change can alter the perceived speed and direction of motion. This chapter covers crossover motion; reverse phi, in which motion between a positive and a negative appears to go backward; the bicycle spokes illusion; the footsteps effect, in which smooth movement looks jerky if the background is striped; zigzag motion, whose direction appears to change with viewing distance; and the furrow illusion of motion, whose direction appears to change when viewed by the fovea versus the periphery. Other concepts covered include the chopstick illusion and the footsteps illusion.

Low-level integration of auditory and visual motion signals requires spatial co-localisation

2005 ◽  
Vol 166 (3-4) ◽  
pp. 538-547 ◽  
Author(s):  
Georg F. Meyer ◽  
Sophie M. Wuerger ◽  
Florian Röhrbein ◽  
Christoph Zetzsche
Keyword(s):  
Visual Motion ◽  
Low Level

scholarly journals Integration of motion energy from overlapping random background noise increases perceived speed of coherently moving stimuli

2016 ◽  
Vol 116 (6) ◽  
pp. 2765-2776 ◽  
Author(s):  
Jason Chuang ◽  
Emily C. Ausloos ◽  
Courtney A. Schwebach ◽  
Xin Huang
Keyword(s):  
Noise Level ◽  
Background Noise ◽  
Visual Motion ◽  
Random Motion ◽  
Spatial Integration ◽  
Neural Basis ◽  
Motion Energy ◽  
Background Stimulus ◽  
Speed Perception ◽  
Perceived Speed

The perception of visual motion can be profoundly influenced by visual context. To gain insight into how the visual system represents motion speed, we investigated how a background stimulus that did not move in a net direction influenced the perceived speed of a center stimulus. Visual stimuli were two overlapping random-dot patterns. The center stimulus moved coherently in a fixed direction, whereas the background stimulus moved randomly. We found that human subjects perceived the speed of the center stimulus to be significantly faster than its veridical speed when the background contained motion noise. Interestingly, the perceived speed was tuned to the noise level of the background. When the speed of the center stimulus was low, the highest perceived speed was reached when the background had a low level of motion noise. As the center speed increased, the peak perceived speed was reached at a progressively higher background noise level. The effect of speed overestimation required the center stimulus to overlap with the background. Increasing the background size within a certain range enhanced the effect, suggesting spatial integration. The speed overestimation was significantly reduced or abolished when the center stimulus and the background stimulus had different colors, or when they were placed at different depths. When the center- and background-stimuli were perceptually separable, speed overestimation was correlated with perceptual similarity between the center- and background-stimuli. These results suggest that integration of motion energy from random motion noise has a significant impact on speed perception. Our findings put new constraints on models regarding the neural basis of speed perception.

Discrimination and Detection of Changes in the Velocity of Visual Motion: Effect of Aperture Size

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 239-239
Author(s):  
L Likova ◽  
G Dimitrov ◽  
S Mateeff ◽  
J Hohnsbein
Keyword(s):  
Change Detection ◽  
Discrimination Task ◽  
Critical Frequency ◽  
Visual Motion ◽  
Critical Factor ◽  
Detection Task ◽  
Viewing Distance ◽  
Aperture Size ◽  
Mean Velocity ◽  
The Subject

Recently Mateeff and Hohnsbein (1996 Vision Research36 2873 – 2882) showed that the critical frequency for detection of modulated velocity of motion was invariant with respect to the viewing distance. The critical frequency was a function of the ratio between the mean velocity and the size of the aperture through which the motion was observed. In the present study we examined whether the velocity/aperture ratio affects velocity discrimination and detection of single velocity changes. Six subjects observed a random-dot pattern that could move within an invisible square aperture. In the discrimination task, two motions of 250 ms duration with slightly different velocities were presented with a 1 s interval between them. The subject had to report which of the motions was faster. In the change-detection task the same two motions were presented without an interval between them and the subject had to report whether the change was from a low to a high velocity or vice versa. Mean velocities of 8 and 64 deg s−1 and aperture sizes of 10 and 40 deg were employed in both tasks. Weber fractions were determined by the method of constant stimuli. The discrimination accuracy was not affected by aperture size at either mean velocity. The detection task was also unaffected by aperture size at 8 deg s−1. However, at 64 deg s−1 decreasing aperture size impaired the Weber fractions by a factor of about three. We suggest that the decrease of the lifetime of the dots of the pattern at high velocities and small apertures may be the critical factor for the impairment of the change detection. This factor is of less importance for the velocity discrimination task.

scholarly journals Influence of Visual Motion on Tactile Motion Perception

2006 ◽  
Vol 96 (3) ◽  
pp. 1625-1637 ◽  
Author(s):  
S. J. Bensmaïa ◽  
J. H. Killebrew ◽  
J. C. Craig
Keyword(s):  
Visual Stimulus ◽  
Visual Motion ◽  
Temporal Frequency ◽  
Sensory Level ◽  
Temporal Synchrony ◽  
Tactile Stimuli ◽  
Tactile Interaction ◽  
Visual Distractors ◽  
Speed Discrimination ◽  
Perceived Speed

Subjects were presented with pairs of tactile drifting sinusoids and made speed discrimination judgments. On some trials, a visual drifting sinusoid, which subjects were instructed to ignore, was presented simultaneously with one of the two tactile stimuli. When the visual and tactile gratings drifted in the same direction (i.e., from left to right), the visual distractors were found to increase the perceived speed of the tactile gratings. The effect of the visual distractors was proportional to their temporal frequency but not to their perceived speed. When the visual and tactile gratings drifted in opposite directions, the distracting effect of the visual distractors was either substantially reduced or, in some cases, reversed (i.e., the distractors slowed the perceived speed of the tactile gratings). This result suggests that the observed visual-tactile interaction is dependent on motion and not simply on the oscillations inherent in drifting sinusoids. Finally, we find that disrupting the temporal synchrony between the visual and tactile stimuli eliminates the distracting effect of the visual stimulus. We interpret this latter finding as evidence that the observed visual-tactile interaction operates at the sensory level and does not simply reflect a response bias.

scholarly journals Eye movements affect the perceived speed of visual motion

1999 ◽  
Vol 39 (6) ◽  
pp. 1177-1187 ◽  
Author(s):  
Kathleen A Turano ◽  
Susan M Heidenreich
Keyword(s):  
Eye Movements ◽  
Visual Motion ◽  
Perceived Speed

Motor Scaling By Viewing Distance of Early Visual Motion Signals During Smooth Pursuit

2002 ◽  
Vol 88 (5) ◽  
pp. 2880-2885 ◽  
Author(s):  
Hui-Hui Zhou ◽  
Min Wei ◽  
Dora E. Angelaki
Keyword(s):  
Eye Movements ◽  
Visual Motion ◽  
Neural Substrates ◽  
Open Loop ◽  
Target Distance ◽  
Viewing Distance ◽  
Major Pathway ◽  
Gaze Stabilization ◽  
Order Of Magnitude ◽  
Eye Velocity

The geometry of gaze stabilization during head translation requires eye movements to scale proportionally to the inverse of target distance. Such a scaling has indeed been demonstrated to exist for the translational vestibuloocular reflex (TVOR), as well as optic flow–selective translational visuomotor reflexes (e.g., ocular following, OFR). The similarities in this scaling by a neural estimate of target distance for both the TVOR and the OFR have been interpreted to suggest that the two reflexes share common premotor processing. Because the neural substrates of OFR are partly shared by those for the generation of pursuit eye movements, we wanted to know if the site of gain modulation for TVOR and OFR is also part of a major pathway for pursuit. Thus, in the present studies, we investigated in rhesus monkeys whether initial eye velocity and acceleration during the open-loop portion of step ramp pursuit scales with target distance. Specifically, with visual motion identical on the retina during tracking at different distances (12, 24, and 60 cm), we compared the first 80 ms of horizontal pursuit. We report that initial eye velocity and acceleration exhibits either no or a very small dependence on vergence angle that is at least an order of magnitude less than the corresponding dependence of the TVOR and OFR. The results suggest that the neural substrates for motor scaling by target distance remain largely distinct from the main pathway for pursuit.

Oculomotor contribution to the change in perceived speed with viewing distance

2008 ◽  
Vol 25 (11) ◽  
pp. 2851 ◽  
Author(s):  
George A. Geri ◽  
Byron J. Pierce ◽  
Robert Patterson
Keyword(s):  
Viewing Distance ◽  
Perceived Speed
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