The Pulfrich Pendulum Phenomenon in Stereoblind Subjects

Perception ◽  
1993 ◽  
Vol 22 (1) ◽  
pp. 7-14 ◽  
Author(s):  
Peter Thompson ◽  
Vicky Wood
Keyword(s):  
Depth Perception ◽  
Interocular Transfer ◽  
Neutral Density ◽  
Neutral Density Filter ◽  
Frontoparallel Plane ◽  
The Third ◽  
Random Dot Stereograms ◽  
High Acuity ◽  
Density Filter ◽  
Pulfrich Effect

The Pulfrich pendulum phenomenon, in which a pendulum swinging in the frontoparallel plane appears to swing in an ellipse when a neutral density filter is placed over one eye of the observer, was investigated in stereoblind subjects. It was found that such subjects can report the presence of the Pulfrich effect although they fail to fuse random-dot stereograms and fail to exhibit interocular transfer of the movement aftereffect. These findings suggest that ‘stereoblind’ subjects must retain some residual binocular mechanism for depth perception. Three possibilities are considered: (i) the stereoblind may be able to utilise contiguous temporal disparities as a cue for depth in the Pulfrich effect; (ii) they may retain some residual binocularity, sufficient to reveal the Pulfrich effect but not for other more demanding tasks for the binocular mechanisms; and (iii) they may retain some coarse magnocellular pathway disparity mechanism having lost their high-acuity parvocellular disparity system. There is little evidence to support any of these hypotheses, but the third shows promise.

Influence of Peripheral on Central Stereopsis: An Induced Depth Tilt Effect

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 276-276
Author(s):  
S Müller ◽  
E R Wist
Keyword(s):  
Opposite Direction ◽  
Rotation Speed ◽  
Neutral Density ◽  
Neutral Density Filter ◽  
Disk Rotation ◽  
Optimal Rotation ◽  
Density Filter ◽  
Pulfrich Effect ◽  
Variable Errors ◽  
Tilted Disk

A large rotating black/white sectored disk (58 deg diameter) viewed with a neutral density filter over one eye is perceived as tilted in depth according to the Pulfrich phenomenon. But with fixation on a centrally located vertical bar (7 deg in length), the disk is perceived as vertical while the central bar is perceived as tilted in the opposite direction. This effect remains even if the central 38 deg portion of the disk is occluded leaving a peripheral annulus 10 deg in width. At an optimal rotation speed of 45° s−1 and a filter of 2 log units, the inter-individual perceived tilt of the bar ranges between 5° and 10° as measured by nulling out the illusory tilt by adjustment with a joystick. Variable errors were extremely small and corresponded well with central stereoscopic resolution. The amount of illusory tilt depends on the speed of disk rotation and filter density, and its direction on the relation between the direction of motion and the filter-covered eye. The effect is not limited to Pulfrich-induced stereotilt: When the disk was stationary but physically tilted in depth, the induced tilt on the central bar corresponded to about 50% of the physical tilt. This effect, in turn, could be cancelled or enhanced by rotating the tilted disk and inducing an appropriate Pulfrich effect. With monocular viewing no induced depth tilt occurs. The results are interpreted in terms of a stereoscopic induced effect operating beyond the known peripheral limits of stereopsis.

A novel consistent photomicrography technique using a reference slide made of neutral density filter

2010 ◽  
Vol 74 (5) ◽  
pp. 397-400 ◽  
Author(s):  
Jong Yeob Kim ◽  
Ji Woong Kim ◽  
Soo Hong Seo ◽  
Young Chul Kye ◽  
Hyo Hyun Ahn
Keyword(s):  
Neutral Density ◽  
Neutral Density Filter ◽  
Density Filter

A Broad-band Neutral Density Filter

1974 ◽  
Vol 21 (10) ◽  
pp. 839-840 ◽  
Author(s):  
D. Flint ◽  
P. Baumeister
Keyword(s):  
Broad Band ◽  
Neutral Density ◽  
Neutral Density Filter ◽  
Density Filter

Younger and Older Adults' Perception of the Wundt-Hering Illusion as a Function of Display Illumination and Reflectance Contrast

1991 ◽  
Vol 73 (1) ◽  
pp. 124-126 ◽  
Author(s):  
Eileen Astor-Stetson ◽  
Susan Lane
Keyword(s):  
College Students ◽  
Older Adults ◽  
Brightness Contrast ◽  
Neutral Density ◽  
Neutral Density Filter ◽  
High Contrast ◽  
Density Filter

Reflectance contrast (i.e., black as compared to grey figures on white ground) and display illumination were manipulated to vary the brightness contrast of Wundt-Hering figures. 16 college students and 16 older adults were presented with high, medium, and low reflectance contrast figures. For half the participants, display illumination was manipulated by covering the figures with a .5 yellow neutral density filter. Magnitude of the illusion increased significantly with increased reflectance contrast for college students, and college students were significantly more susceptible to the high contrast figures than were older adults. Display illumination had no effect on the performance of either group.

scholarly journals Investigation of 1064-nm laser damage mechanism of neutral density filter

2012 ◽  
Vol 61 (7) ◽  
pp. 076102
Author(s):  
Liu Yan-Yan ◽  
Han Jing-Hua ◽  
Duan Tao ◽  
Niu Rui-Hua ◽  
Sun Nian-Chun ◽  
...  
Keyword(s):  
Damage Mechanism ◽  
Laser Damage ◽  
Neutral Density ◽  
Neutral Density Filter ◽  
Density Filter

scholarly journals A yellow filter improves response times to low-contrast targets and traffic hazards

2019 ◽  
Author(s):  
Philippe Lacherez ◽  
Alexander K Saeri ◽  
Joanne Wood ◽  
David Atchison ◽  
Mark Horswill
Keyword(s):  
Response Times ◽  
Neutral Density ◽  
Neutral Density Filter ◽  
Hazard Perception ◽  
Low Contrast ◽  
Perception Task ◽  
Yellow Filter ◽  
Visual Tasks ◽  
Density Filter ◽  
Video Presentations

Purpose: Anecdotal evidence suggests that some sunglass users prefer yellow tints for outdoor activities such as driving, and research has suggested that such tints improve the apparent contrast and brightness of real-world objects. The aim of this study was to establish whether yellow filters resulted in objective improvements in performance for visual tasks relevant to driving.Methods: Response times of nine young (age 31.4 ± 6.7 years) and nine older (age 74.6 ± 4.8) adults were measured using (a) video presentations of traffic hazards (driving hazard perception task), and (b) a simple low-contrast grating which appeared at random peripheral locations on a computer screen. Response times were compared when participants wore a yellow filter (with and without a linear polariser) versus a neutral density filter (with and without a linear polariser). All lens combinations were matched to have similar luminance transmittances (approximately 27%). Results: In the driving hazard perception task, the young but not the older participants responded significantly more rapidly to hazards when wearing a yellow filter than with a luminance matched neutral density filter (mean difference 450 ms). In the low-contrast grating task, younger participants also responded more quickly for the yellow filter condition but only when combined with a polariser. Although response times increased with increasing stimulus eccentricity for the low-contrast grating task, for the younger participants this slowing of response times with increased eccentricity was reduced in the presence of a yellow filter, indicating that perception of more peripheral objects may be improved by this filter combination. Conclusions: Yellow filters improve response times for younger adults for visual tasks relevant to driving.

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