The Task-Dependent use of Binocular Disparity and Motion Parallax under Natural Viewing Conditions

The use of binocular disparity and motion parallax information was compared in three different psychophysical tasks for which natural viewing and physical stimuli were used. Natural viewing may be an important factor in interpreting experiments which have addressed the ability to use disparity and parallax both separately and in combination (see Frisby et al, 1996 Perception25 129 – 154). The stimuli consisted of configurations of three bright LEDs carefully aligned in the horizontal meridian and presented in darkness. The distance of the middle LED (flashing at 5 Hz) could be adjusted along the midline in accordance with the tasks which included: (i) a depth nulling task, (ii) a depth matching task, and (iii) a shape task—match base/height of triangle. Each task was performed at two viewing distances (1.5 and 3.0 m) and under four different viewing conditions: (i) monocular-static, (ii) monocular-moving, (iii) binocular-static, and (iv) binocular-moving. Note that the different tasks differ in their dependence on viewing distance, and the available cues for viewing distance differ between viewing conditions. Four observers made ten settings in each condition at each distance. Observers, as expected, performed badly (bias and accuracy) in all tasks in the monocular-static condition. Nulling was accurate in the other viewing conditions (no estimate of viewing distance required). Performance was best in the matching task (ratio of viewing distances) but although binocular-static was significantly better than monocular-moving performance in this and in the shape task (absolute distance required), there was no additional improvement in the binocular-moving condition. Results show that observers can recover structure accurately from parallax or disparity information in real-world stimuli.

Download Full-text

Does Vision Extract Absolute Distance from Vergence?

10.1101/731109 ◽

2019 ◽

Author(s):

Paul Linton

Keyword(s):

Binocular Disparity ◽

Motion Parallax ◽

Absolute Distance ◽

Angular Rotation ◽

Visual Scale ◽

First Time ◽

Real Challenge

AbstractSince Kepler (1604) and Descartes (1638), ‘vergence’ (the angular rotation of the eyes) has been thought of as one of our most important absolute distance cues. But vergence has never been tested as an absolute distance cue divorced from obvious confounding cues such as binocular disparity. In this article we control for these confounding cues for the first time by gradually manipulating vergence, and find that observers fail to accurately judge distance from vergence. We consider a number of different interpretations of these results, and argue that the most principled response to these results is to question the general effectiveness of vergence as an absolute distance cue. Given other absolute distance cues (such as motion parallax and vertical disparities) are limited in application, this poses a real challenge to our contemporary understanding of visual scale.

Download Full-text

PERFORMANCE OF PROGENY OF FINNISH LANDRACE AND DORSET HORN RAMS MATED TO EWES OF VARIOUS BREEDS AND CROSSES

Canadian Journal of Animal Science ◽

10.4141/cjas78-052 ◽

1978 ◽

Vol 58 (3) ◽

pp. 399-408

Author(s):

J. A. VESELY

Keyword(s):

Average Score ◽

Weaning Weight ◽

Additional Improvement ◽

Carcass Merit ◽

Breed Crosses ◽

Better Than

Over a 3-yr period, 1,556 lambs were produced from matings of Dorset Horn and Finnish Landrace rams to ewes of the Romnelet, Columbia, Suffolk, and North Country Cheviot breeds and their 2-, 3-, and 4-breed crosses. Also, 142 purebred lambs of the four dam breeds were produced as a basis for contemporary comparisons. The average weaning weight of the purebred lambs was 23.7 ± 0.4 kg; of the 2-breed cross lambs, ½-Dorset lambs averaged 25.1 ± 0.5 kg and ½-Finnish Landrace 25.6 ± 0.5 kg. The 3-breed cross ½-Dorset lambs averaged 27.1 ± 0.4 kg and ½-Finnish Landrace lambs 26.1 ± 0.4 kg; and 4-breed cross ½-Dorset lambs 27.1 ± 0.4 kg and ½-Finnish Landrace lambs 26.8 ± 0.4 kg. The 5-breed cross ½-Dorset and ½-Finnish Landrace lambs both averaged about 27.5 ± 0.5 kg. Weight-per-day-of-age to market weight showed the same trend as weaning weight among the purebred and crossbred lambs. Purebred lambs were exceeded by 2-breed cross lambs in weaning weight (7%) and weight-per-day-of-age to market weight (6%) and by 3-breed cross lambs (13% and 8%, respectively). No practical additional improvement for either trait was evident in 4-breed and 5-breed crosses. Two-breed cross ewes (Romnelet × Suffolk and Columbia × Suffolk) raised lambs of about the same weaning weight (27.7 and 27.3 kg) as the 3-breed and 4-breed cross ewes (24.9–27.4 kg). Dorset Horn and Finnish Landrace rams contributed about equally to weaning weights (26.6 and 26.5 kg) and weight-per-day-of-age to market weight (0.241 and 0.236 kg). The average score of the ½-Finnish Landrace carcasses was slightly, but significantly, better than that of the ½-Dorset Horn carcasses. Both Dorset Horn and Finnish Landrace rams produced crossbred lambs with satisfactory growth and carcass merit.

Download Full-text

Percept of shape distortion induced by binocular disparity and motion parallax

Journal of Vision ◽

10.1167/10.7.43 ◽

2010 ◽

Vol 10 (7) ◽

pp. 43-43

Author(s):

M. Ishii ◽

M. Sato

Keyword(s):

Binocular Disparity ◽

Motion Parallax ◽

Shape Distortion

Download Full-text

Improvement of Absolute Distance Estimation Under Water: Use of Monocular Motion Parallax

10.21236/ad0763396 ◽

1973 ◽

Author(s):

Steven H. Ferris

Keyword(s):

Water Use ◽

Motion Parallax ◽

Distance Estimation ◽

Absolute Distance

Download Full-text

Better to Be Alone than in Bad Company: Cognate Synonyms Impair Word Learning

Behavioral Sciences ◽

10.3390/bs10080123 ◽

2020 ◽

Vol 10 (8) ◽

pp. 123

Author(s):

Eneko Antón ◽

Jon Andoni Duñabeitia

Keyword(s):

Word Learning ◽

Word Association ◽

Recognition Task ◽

The Other ◽

Matching Task ◽

L2 Acquisition ◽

New Words ◽

L2 Word Learning ◽

Concrete Concepts ◽

Better Than

The effects of cognate synonymy in L2 word learning are explored. Participants learned the names of well-known concrete concepts in a new fictional language following a picture-word association paradigm. Half of the concepts (set A) had two possible translations in the new language (i.e., both words were synonyms): one was a cognate in participants’ L1 and the other one was not. The other half of the concepts (set B) had only one possible translation in the new language, a non-cognate word. After learning the new words, participants’ memory was tested in a picture-word matching task and a translation recognition task. In line with previous findings, our results clearly indicate that cognates are much easier to learn, as we found that the cognate translation was remembered much better than both its non-cognate synonym and the non-cognate from set B. Our results also seem to suggest that non-cognates without cognate synonyms (set B) are better learned than non-cognates with cognate synonyms (set A). This suggests that, at early stages of L2 acquisition, learning a cognate would produce a poorer acquisition of its non-cognate synonym, as compared to a solely learned non-cognate. These results are discussed in the light of different theories and models of bilingual mental lexicon.

Download Full-text

Motion Parallax as an Independent Cue for Depth Perception

Perception ◽

10.1068/p080125 ◽

1979 ◽

Vol 8 (2) ◽

pp. 125-134 ◽

Cited By ~ 432

Author(s):

Brian Rogers ◽

Maureen Graham

Keyword(s):

Depth Perception ◽

Close Agreement ◽

Motion Parallax ◽

Three Dimensional ◽

Matching Task ◽

Relative Depth ◽

Relative Movement ◽

Random Dot Stereograms ◽

Random Dot Patterns ◽

Dimensional Surface

The perspective transformations of the retinal image, produced by either the movement of an observer or the movement of objects in the visual world, were found to produce a reliable, consistent, and unambiguous impression of relative depth in the absence of all other cues to depth and distance. The stimulus displays consisted of computer-generated random-dot patterns that could be transformed by each movement of the observer or the display oscilloscope to simulate the relative movement information produced by a three-dimensional surface. Using a stereoscopic matching task, the second experiment showed that the perceived depth from parallax transformations is in close agreement with the degree of relative image displacement, as well as producing a compelling impression of three-dimensionality not unlike that found with random-dot stereograms.

Download Full-text

Effects of Viewing Distance and Visual Angle on Metameric Matches

Perceptual and Motor Skills ◽

10.2466/pms.1982.54.1.119 ◽

1982 ◽

Vol 54 (1) ◽

pp. 119-126

Author(s):

Ranald R. MacDonald ◽

Francis Pratt ◽

Martin E. Beattie

Keyword(s):

Visual Angle ◽

Matching Task ◽

Viewing Distance

A metameric matching task was used to study the effect of viewing distance and visual angle on the appearance of bichromatic stimuli. Increasing the viewing distance resulted in a shift towards the longer wavelength component. Effects of visual angle were also found.

Download Full-text

Perception of Slope in Photographs

Perception ◽

10.1068/v970323 ◽

1997 ◽

Vol 26 (1_suppl) ◽

pp. 179-179

Author(s):

J W Huber ◽

I R L Davies

Keyword(s):

Focal Length ◽

Matching Task ◽

Task Characteristics ◽

Viewing Distance ◽

Free Viewing ◽

Texture Characteristics ◽

Wide Angle Lens ◽

Available Information ◽

Practical Implications ◽

Station Point

Perceptions of characteristics of space such as slope, distance, and depth are frequently inaccurate, both in the real world and in pictures. We carried out experiments to study factors that influence the accuracy of perceived slope in photographs. Slopes varied in angle from 5° to 45° inclinations against the horizontal, and in the information available to the observer (outline shape and texture characteristics). We found that perceived slope is correlated with real slope ( r=0.99), but that observers consistently overestimate slope. The latter depends not only on the available information, but also on the focal length of the lens with which slopes were photographed. Overestimation is less pronounced for the wide-angle lens compared to the standard lens. A comparison of free viewing and viewing from the correct station-point showed that the latter leads to less overestimation of slope. Since the viewing distance was too far under free viewing, the results are compatible with geometrical optics. In a further experiment the effects of magnification and minification were studied by deliberately viewing the photographs from fixed points closer or further away than the station-point; this led to an increase and decrease in overestimation, respectively. Finally, results are frequently dependent on task characteristics: magnitude judgements of photographs without an anchoring point can only be accurate to a level of scale. Thus using an action-based matching task may lead to more accurate slope perception. We therefore carried out a comparison experiment using a matching task to check for the generality and action-dependence of our results. Practical implications for the use of photographs as surrogates for natural viewing are discussed.

Download Full-text

The Radio Properties of SNRs in the Magellanic Clouds

Symposium - International Astronomical Union ◽

10.1017/s0074180900034422 ◽

1983 ◽

Vol 101 ◽

pp. 551-558 ◽

Cited By ~ 1

Author(s):

B. Y. Mills

Keyword(s):

Supernova Remnants ◽

Average Distance ◽

Hii Regions ◽

Magellanic Clouds ◽

Selection Effects ◽

Absolute Distance ◽

Major Difficulty ◽

Order Of Magnitude ◽

Thermal Sources ◽

Better Than

An understanding of the radio properties and evolution of Galactic supernova remnants has always been hampered by the difficulty of measuring distances. A conventional wisdom has developed around a set of ‘good’ calibrators but most workers involved have drawn attention to the uncertainties and the possibility of selection effects distorting results. This major difficulty is completely overcome by studying SNRs in the Magellanic Clouds. Although there is uncertainty in the absolute distance scale, relative distances can be determined to better than 10% and differences of this magnitude are not significant when intercomparing SNRs. There is, however, another set of problems associated with sensitivity and resolution. The Clouds are an order of magnitude more distant than the average distance of Galactic SNRs, thus many of the SNRs are close to or below the sensitivity limits of most of the southern radiotelescopes and, until recently, the resolution available has often been inadequate to separate non-thermal sources from thermal HII regions, so that both flux densities and spectra have been subject to error. Also there are ∼ 1000 extragalactic background sources which can mimic the flux density and spectra of SNRs in the Clouds, particularly when close to or behind HII regions; as a result numerous incorrect or doubtful SNR identifications have been suggested.

Download Full-text