The Ponzo Illusion in Virtual Environments: Correctly Applied Size Constancy?

1996 ◽  
Vol 40 (11) ◽  
pp. 551-554
Author(s):  
Robert A. King ◽  
Greg E. Fujawa ◽  
Kelly G. Elliott
Keyword(s):  
Effect Size ◽  
Rating Scale ◽  
Linear Trend ◽  
Relative Size ◽  
Ponzo Illusion ◽  
Linear Perspective ◽  
Size Constancy ◽  
Relative Height ◽  
Significant Linear Trend ◽  
Depth Cues

The perceived size of a stimulus can be greatly influenced by the surrounding depth cues. The effect size of the Ponzo Illusion was tested in a virtual environment with many depth cues (MC) and few depth cues (FC) conditions. The effect of size and the depth cues on the perceived proximal size of the stimulus was measured. Methods. A modified Wheatstone stereoscope was used to present the stimuli on a monitor positioned 80 cm from the subjects. The subjects used a 6AFC confidence rating scale to indicate whether the first or second of two sequentially presented stimuli had a greater proximal extent. The ‘many cues’ (MC) condition included texture, relative height, foreshortening, linear perspective, relative brightness, and relative size. The few cues condition consisted of linear perspective, relative height, and relative size. Stimulus size (proximal extent) was varied independently from all other depth cues. Results. Both depth cue context and proximal size were found to have a significant effect on the perceived proximal size for FC conditions. However, for MC conditions only the depth cues, and not proximal size, had an effect on perceived proximal size. The effect size for both depth cues and proximal size had a significant linear trend. But proximal size had a larger trend that was significantly related to the size constancy function.

The Perception of Distance in Simulated Visual Displays:A Comparison of the Effectiveness and Accuracy of Multiple Depth Cues Across Viewing Distances

1997 ◽  
Vol 6 (5) ◽  
pp. 513-531 ◽  
Author(s):  
R. Troy Surdick ◽  
Elizabeth T. Davis ◽  
Robert A. King ◽  
Larry F. Hodges
Keyword(s):  
Relative Size ◽  
Linear Perspective ◽  
Depth Information ◽  
Texture Gradient ◽  
Viewing Distance ◽  
Relative Height ◽  
Distance Information ◽  
Depth Cues ◽  
Relative Brightness ◽  
Depth Cue

The ability effectively and accurately to simulate distance in virtual and augmented reality systems is a challenge currently facing R&D. To examine this issue, we separately tested each of seven visual depth cues (relative brightness, relative size, relative height, linear perspective, foreshortening, texture gradient, and stereopsis) as well as the condition in which all seven of these cues were present and simultaneously providing distance information in a simulated display. The viewing distances were 1 and 2 m. In developing simulated displays to convey distance and depth there are three questions that arise. First, which cues provide effective depth information (so that only a small change in the depth cue results in a perceived change in depth)? Second, which cues provide accurate depth information (so that the perceived distance of two equidistant objects perceptually matches)? Finally, how does the effectiveness and accuracy of these depth cues change as a function of the viewing distance? Ten college-aged subjects were tested with each depth-cue condition at both viewing distances. They were tested using a method of constant stimuli procedure and a modified Wheat-stone stereoscopic display. The perspective cues (linear perspective, foreshortening, and texture gradient) were found to be more effective than other depth cues, while effectiveness of relative brightness was vastly inferior. Moreover, relative brightness, relative height, and relative size all significantly decreased in effectiveness with an increase in viewing distance. The depth cues did not differ in terms of accuracy at either viewing distance. Finally, some subjects experienced difficulty in rapidly perceiving distance information provided by stereopsis, but no subjects had difficulty in effectively and accurately perceiving distance with the perspective information used in our experiment. A second experiment demonstrated that a previously stereo-anomalous subject could be trained to perceive stereoscopic depth in a binocular display. We conclude that the use of perspective cues in simulated displays may be more important than the other depth cues tested because these cues are the most effective and accurate cues at both viewing distances, can be easily perceived by all subjects, and can be readily incorporated into simpler, less complex displays (e.g., biocular HMDs) or more complex ones (e.g., binocular or see-through HMDs).

Relative Height and Relative Size as Monocular Depth Cues in the Trapezoid

1966 ◽  
Vol 22 (1) ◽  
pp. 275-281 ◽  
Author(s):  
Bruce E. Dunn ◽  
Stuart W. Thomas
Keyword(s):  
Relative Size ◽  
Frontal Plane ◽  
Vertical Axis ◽  
Vertical Edge ◽  
Relative Height ◽  
Depth Cues ◽  
Horizontal Length ◽  
Monocular Depth Cues ◽  
Monocular Depth

Ss viewed trapezoids and made absolute judgments of their degree of tilt around a vertical axis. The trapezoids were equal in horizontal length but the ratio of their vertical edges was 15:16 or 13:16. The height in the frontal plane of the midpoint of the shorter vertical edge varied from above (positive) to below (negative) the midpoint height of the longer vertical edge. Two extremes in the type of function to expect were predicted on the basis of past experimentation and geometric considerations. It was found that as the relative midpoint height went from negative to positive, perceived tilt increased linearly except for a brief reversal in the 15:16 condition. Perceived tilt was shown to be greater, but with some overlap, for the 13:16 trapezoids.

Infant Macaque Monkeys Respond to Pictorial Depth

1993 ◽  
Vol 4 (2) ◽  
pp. 93-98 ◽  
Author(s):  
Virginia M. Gunderson ◽  
Albert Yonas ◽  
Patricia L. Sargent ◽  
Kimberly S. Grant-Webster
Keyword(s):  
Relative Size ◽  
Macaca Nemestrina ◽  
Linear Perspective ◽  
Primate Species ◽  
Depth Information ◽  
Texture Gradient ◽  
Depth Cues ◽  
Western Art ◽  
Pictorial Depth ◽  
Nonhuman Primate Species

The studies described here are the first to demonstrate that a nonhuman primate species is capable of responding to pictorial depth information during infancy. In two experiments, pigtailed macaque ( Macaca nemestrina) infants were tested for responsivity to the pictorial depth cues of texture gradient/linear perspective and relative size. The procedures were adapted from human studies and are based on the proclivity of infants to reach more frequently to closer objects than to objects that are farther away. The stimulus displays included two equidistant objects that, when viewed monocularly, appear separated in space because of an illusion created by pictorial depth cues. When presented with these displays, animals reached significantly more often to the apparently closer objects under monocular conditions than under binocular conditions. These findings suggest that infant macaques are sensitive to pictorial depth information, the implication being that this ability has ancient phylogenetic origins and is not learned from exposure to the conventions of Western art.

Relevant Cues for the Visual Perception of Depth: Is Where You See it Where it is?

1994 ◽  
Vol 38 (19) ◽  
pp. 1305-1309 ◽  
Author(s):  
R. Troy Surdick ◽  
Elizabeth T. Davis ◽  
Robert A. King ◽  
Gregory M. Corso ◽  
Alexander Shapiro ◽  
...  
Keyword(s):  
Spatial Perception ◽  
Relative Size ◽  
Linear Perspective ◽  
Depth Information ◽  
Texture Gradient ◽  
Viewing Distance ◽  
Stereoscopic Display ◽  
Depth Cues ◽  
Relative Brightness ◽  
Depth Cue

We tested seven visual depth cues (relative brightness, relative size, relative height, linear perspective, foreshortening, texture gradient, and stereopsis) at viewing distances of one and two meters to answer two questions. First, which cues provide effective depth information (i.e., only a small change in the depth cue results in a noticeable change in perceived depth). Second, how does the effectiveness of these depth cues change as a function of the viewing distance? Six college-aged subjects were tested with each depth cue at both viewing distances. They were tested using a method of constant stimuli procedure and a modified Wheatstone stereoscopic display. Accuracies for perceptual match settings for all cues were very high (mean constant errors were near zero), and no cues were significantly more or less accurate than any others. Effectiveness of the perspective cues (linear perspective, foreshortening, and texture gradient) was superior to that of other depth cues, while effectiveness of relative brightness was vastly inferior. Moreover, stereopsis, among the more effective cues at one meter, was significantly less so at two meters. These results have theoretical implications for models of human spatial perception and practical implications for the design and development of 3D virtual environments.

scholarly journals Thirty-Nine-Year Wave Hindcast, Storm Activity, and Probability Analysis of Storm Waves in the Kara Sea, Russia

Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 648
Author(s):  
Stanislav Myslenkov ◽  
Vladimir Platonov ◽  
Alexander Kislov ◽  
Ksenia Silvestrova ◽  
Igor Medvedev
Keyword(s):  
Climate Change ◽  
Pareto Distribution ◽  
Linear Trend ◽  
Wind Waves ◽  
Kara Sea ◽  
The Arctic ◽  
Storm Events ◽  
Storm Activity ◽  
Significant Linear Trend ◽  
The Impact

The recurrence of extreme wind waves in the Kara Sea strongly influences the Arctic climate change. The period 2000–2010 is characterized by significant climate warming, a reduction of the sea ice in the Arctic. The main motivation of this research to assess the impact of climate change on storm activity over the past 39 years in the Kara Sea. The paper presents the analysis of wave climate and storm activity in the Kara Sea based on the results of numerical modeling. A wave model WAVEWATCH III is used to reconstruct wind wave fields for the period from 1979 to 2017. The maximum significant wave height (SWH) for the whole period amounts to 9.9 m. The average long-term SWH for the ice-free period does not exceed 1.3 m. A significant linear trend shows an increase in the storm wave frequency for the period from 1979 to 2017. It is shown that trends in the storm activity of the Kara Sea are primarily regulated by the ice. Analysis of the extreme storm events showed that the Pareto distribution is in the best agreement with the data. However, the extreme events with an SWH more than 6‒7 m deviate from the Pareto distribution.

Cylindrocarpon and Fusarium root colonization of Douglas-fir seedlings from British Columbia reforestation sites

1998 ◽  
Vol 28 (8) ◽  
pp. 1198-1206 ◽  
Author(s):  
Paige E Axelrood ◽  
William K Chapman ◽  
Keith A Seifert ◽  
David B Trotter ◽  
Gwen Shrimpton
Keyword(s):  
British Columbia ◽  
Pseudotsuga Menziesii ◽  
Root Colonization ◽  
Linear Trend ◽  
Poor Performance ◽  
Douglas Fir ◽  
Root Infection ◽  
Significant Linear Trend ◽  
Conifer Seedlings ◽  
Cylindrocarpon Destructans

Poor performance of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) plantations established in 1987 has occurred in southwestern British Columbia. Affected sites were planted with 1-year-old container stock that exhibited some root dieback in the nursery. A study was initiated in 1991 to assess Cylindrocarpon and Fusarium root infection in planted and naturally regenerating (natural) Douglas-fir seedlings from seven affected plantations. Percentages of seedlings harboring Cylindrocarpon spp.and percent root colonization were significantly greater for planted seedlings compared with natural seedlings. A significant linear trend in Cylindrocarpon root colonization was observed for planted seedlings with colonization levels being highest for roots closest to the remnants of the root plug and decreasing at distances greater than 10cm from that region. This trend in Cylindrocarpon colonization was not observed for natural seedlings. Cylindrocarpon destructans (Zins.) Scholten var. destructans and C.cylindroides Wollenw. var. cylindroides were the only species isolated from planted and natural conifer seedlings. For most sites, percentage of seedlings harboring Fusarium spp.and percent Fusarium root colonization were less than for Cylindrocarpon. Recovery of Fusarium spp.from seedlings and root colonization levels were not significantly different for planted and natural seedlings from all sites.

Learning as a Function of Subliminal Reinforcements

1963 ◽  
Vol 12 (2) ◽  
pp. 387-398
Author(s):  
Austin Jones ◽  
Melvin Manis ◽  
Bernard Weiner
Keyword(s):  
Relative Frequency ◽  
Probability Learning ◽  
Linear Trend ◽  
Stimulus Category ◽  
Time Intervals ◽  
Significant Linear Trend ◽  
Tachistoscopic Presentation ◽  
Stimulus Classes ◽  
Learning Trials ◽  
Correct Discrimination

Three studies were conducted to assess the effects of subliminal reinforcements on learning. In the first two, Ss were given a discrimination task in which five geometric forms, repeated over 100 trials, were to be assigned to one of two categories. The categories were unbalanced; four geometric forms comprised one category, the remaining form the other. Response was required on each trial. Immediately after each response, the appropriate reinforcing word, “Right” or “Wrong,” was flashed at a subliminal brightness-contrast In Exp. I, under low motivation (without money incentives), Ss showed no learning of the correct discrimination, nor any evidence of probability learning with respect to relative frequency of stimulus categories. In Exp. II, the above procedure was replicated with money as the incentive. There again was no evidence of discrimination learning, i.e., acquisition of the correct response. There was, however, a significant linear trend ( p < .05) in the proportion of responses made to the more frequent stimulus category; Ss showed an increasing tendency to “match” the relative frequency of their two classes of response with the corresponding two stimulus classes. In Exp. III, Ss who were motivated by a money incentive attempted to guess whether E was thinking of an odd or an even number. Following each response, Ss were reinforced by tachistoscopic presentation of the word “Right” or “Wrong,” at time intervals which were too brief to permit recognition; half of the Ss were positively reinforced for emitting the response “Odd,” and half for the response “Even.” After 100 learning trials had been completed, the reinforcement contingencies were switched for an additional 20 trials, e.g., Ss who had been reinforced for “Odd” were now reinforced for “Even.” Ss in Exp. III showed no evidence of probability learning. Some possible explanations for the conflicting results of Exps. II and III were discussed.

Nonsymbolic-Magnitude Deficit in Adults With Developmental Dyscalculia: Evidence of Impaired Size Discrimination but Intact Size Constancy

2021 ◽  
pp. 095679762199520
Author(s):  
Nirit Fooks ◽  
Bat-Sheva Hadad ◽  
Orly Rubinsten
Keyword(s):  
Size Constancy ◽  
Size Discrimination ◽  
Depth Cues ◽  
Developmental Dyscalculia ◽  
Core Deficit ◽  
Depth Ordering

Although researchers have debated whether a core deficit of nonsymbolic representation of magnitude underlies developmental dyscalculia (DD), research has mostly focused on numerosity processing. We probed the possibility of a general magnitude deficit in individuals with DD and asked whether sensitivity to size varied in contexts of depth ordering and size constancy. We measured full psychometric functions in size-discrimination tasks in 12 participants with DD and 13 control participants. Results showed that although people with DD exhibited veridical perceived magnitude, their sensitivity to size was clearly impaired. In contrast, when objects were embedded in depth cues allowing size-constancy computations, participants with DD demonstrated typical sensitivity to size. These results demonstrate a deficit in the perceptual resolutions of magnitude in DD. At the same time, the finding of an intact size constancy suggests that when magnitude perception is facilitated by implicit mandatory computations of size constancy, this deficit is no longer evident.

scholarly journals Clinical Efficacy and Target Engagement of Glutamatergic Drugs: Placebo-Controlled RCTs of Pomaglumetad and TS-134 for Reversal of Ketamine-Induced Psychotic Symptoms and PharmacoBOLD in Healthy Volunteers

2020 ◽  
Author(s):  
Joshua T. Kantrowitz ◽  
Jack Grinband ◽  
Donald C. Goff ◽  
Adrienne C. Lahti ◽  
Stephen R. Marder ◽  
...  
Keyword(s):  
Effect Size ◽  
Metabotropic Glutamate Receptor ◽  
Rating Scale ◽  
Clinical Symptoms ◽  
Anterior Cingulate ◽  
Psychotic Symptoms ◽  
High Dose ◽  
Size Estimation ◽  
Target Engagement ◽  
Dorsal Anterior Cingulate Cortex

AbstractWe tested two metabotropic glutamate receptor 2/3 (mGluR2/3) agonist prodrugs – pomaglumetad (POMA) and TS-134 – including a high-dose of POMA that was four times the dose tested in the failed phase schizophrenia III trials – in two proof of mechanism, Phase Ib studies using identical pharmacoBOLD target-engagement methodology.The POMA study was a double-blind, NIMH-sponsored, 10-day study of 80 or 320 mg/d POMA or placebo (1:1:1 ratio), designed to detect d>0.8 sd between-group effect-size differences. The TS-134 study was a single-blind, industry-sponsored, 6-day study of 20 or 60 mg/d TS-134 or placebo (5:5:2 ratio), designed to permit effect-size estimation for future studies. Primary outcomes were ketamine-induced changes in pharmacoBOLD in the dorsal anterior cingulate cortex (dACC) and Brief Psychiatric Rating Scale (BPRS).95 healthy controls were randomized to POMA and 63 to TS-134. High-dose POMA had significant within and between-group reduction in ketamine-induced BPRS total symptoms (p<0.01, d=-0.41; p=0.04, d=-0.44, respectively) but neither POMA dose significantly suppressed ketamine-induced dACC pharmacoBOLD. In contrast, low-dose TS-134 had significant/trend level, moderate to large within and between group effects on BPRS positive symptoms (p=0.02, d=-0.36; p=0.008, d=-0.82, respectively) and dACC pharmacoBOLD (p=0.004, d=-0.56; p=0.079, d=-0.50, respectively) using pooled across-study placebo data.High-dose POMA exerted significant effects on clinical symptoms, but not on target engagement, suggesting a higher dose may yet be needed. TS-134 20 mg showed evidence of symptom reduction and target engagement, indicating a curvilinear dose-response curve. These results warrant further investigation of mGluR2/3 and other glutamate-targeted treatments for schizophrenia.

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