Nulling the Movement Aftereffect: Evidence for Pattern Specificity

Perception ◽  
1974 ◽  
Vol 3 (3) ◽  
pp. 267-274 ◽  
Author(s):  
J E W Mayhew
Keyword(s):  
Opposite Direction ◽  
Test Surface ◽  
Homogeneous Field ◽  
Movement Aftereffect ◽  
Motion Detectors ◽  
Patterned Illumination ◽  
Two Populations

A microtextured surface such as a homogeneously illuminated tracing-paper screen provides an excellent test surface for the movement aftereffect. When it is moved against the aftereffect at the appropriate velocity, a null occurs and the screen appears stationary. However, if patterned illumination is superimposed on the homogeneous field, the nulling breaks down. The pattern appears to move in one direction, driven by the aftereffect, and the screen can be clearly seen moving in the opposite direction. This breakdown begins to occur at luminances just above threshold for the detection of the pattern. The implication is that two populations of motion detectors are involved. Evidence in support of this postulate is presented.

scholarly journals The Rotating Snakes Illusion Is a Straightforward Consequence of Nonlinearity in Arrays of Standard Motion Detectors

i-Perception ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 204166952095802
Author(s):  
Michael Bach ◽  
Lea Atala-Gérard
Keyword(s):  
Opposite Direction ◽  
Real World ◽  
Illusory Motion ◽  
New Model ◽  
Steady Fixation ◽  
Free Parameters ◽  
Motion Detectors ◽  
Straightforward Consequence ◽  
Real World Situation ◽  
Gray Values

The Rotating Snakes illusion is a motion illusion based on repeating, asymmetric luminance patterns. Recently, we found certain gray-value conditions where a weak illusory motion occurs in the opposite direction. Of the four models for explaining the illusion, one also explains the unexpected perceived opposite direction.We here present a simple new model, without free parameters, based on an array of standard correlation-type motion detectors with a subsequent nonlinearity (e.g., saturation) before summing the detector outputs. The model predicts (a) the pattern-appearance motion illusion for steady fixation, (b) an illusion under the real-world situation of saccades across or near the pattern (pattern shift), (c) a relative maximum of illusory motion for the same gray values where it is found psychophysically, and (d) the opposite illusion for certain luminance values. We submit that the new model’s sparseness of assumptions justifies adding a fifth model to explain this illusion.

scholarly journals Loneliness of the Blind and the Visually Impaired

2021 ◽  
Vol 12 ◽  
Author(s):  
Ami Rokach ◽  
David Berman ◽  
Alison Rose
Keyword(s):  
General Population ◽  
Social Isolation ◽  
Emotional Distress ◽  
Vulnerable Populations ◽  
Opposite Direction ◽  
Growth And Development ◽  
Visually Impaired ◽  
Blind And Visually Impaired ◽  
Social Inadequacy ◽  
Two Populations

Loneliness has been termed a social epidemic, especially when experienced by people with disabilities. In order to better understand how loneliness is experienced in vulnerable populations, the present study compared the qualitative dimensions of loneliness of the blind and visually impaired with the general population not on the frequency or intensity of their loneliness, but on its qualitative aspects. One hundred and eighty-seven participants responded to a questionnaire which measured the qualitative aspects of loneliness on five subscales: Emotional distress, social inadequacy, Growth and discovery, social isolation, and emotional alienation. Results indicated that as expected, the two populations differed significantly in their scores on four of the five subscales (except emotional alienation), but in the opposite direction of what was expected. That may indicate that the visually impaired person’s ability to transcend their blindness, and connect with those around them, and the larger society, in different—and not necessarily less meaningful-manner than the seeing general population. As expected, the visually impaired scored significantly higher than the general population on the Growth and development subscale.

scholarly journals The Rotating Snake Illusion is a straightforward consequence of non-linearity in arrays of standard motion detectors

2020 ◽  
Author(s):  
Michael Bach ◽  
Lea Atala-Gérard
Keyword(s):  
Opposite Direction ◽  
Real World ◽  
Illusory Motion ◽  
New Model ◽  
The Real ◽  
Steady Fixation ◽  
Free Parameters ◽  
Motion Detectors ◽  
Straightforward Consequence ◽  
Real World Situation

AbstractThe Rotating Snakes illusion is a motion illusion based on repeating, asymmetric luminance patterns. Recently, we found certain grey-value conditions where a weak, illusory motion occurs in the opposite direction. Of the four models for explaining the illusion, one (Backus and Oruç, 2005) also explains the unexpected perceived opposite direction. We here present a simple new model, without free parameters, based on an array of standard correlation-type motion detectors with a subsequent non-linearity (e.g., saturation) before summing the detector outputs. The model predicts (1) the pattern-appearance motion illusion for steady fixation, (2) an illusion under the real-world situation of saccades across or near the pattern (pattern shift), (3) a relative maximum of illusory motion for the same grey values where it is found psychophysically, and (4) the inverse illusion for certain luminance values. We submit that the model’s sparseness of assumptions justifies adding a fifth model to explain this illusion.

Is Red Really Romantic?

2017 ◽  
Vol 48 (3) ◽  
pp. 174-183 ◽  
Author(s):  
Gabrielle K. Lehmann ◽  
Robert J. Calin-Jageman
Keyword(s):  
Opposite Direction ◽  
Positive Control ◽  
Weak Effect ◽  
Sample Sizes ◽  
Quality Controls

Abstract. Red has been reported to enhance attraction for women rating men ( Elliot et al., 2010 ) and men rating women ( Elliot & Niesta, 2008 ). We replicated one of these studies online and in-person. To ensure rigor, we obtained original materials, planned for informative sample sizes, pre-registered our study, used a positive control, and adopted quality controls. For men, we found a very weak effect in the predicted direction (d = 0.09, 95% CI [−0.17, 0.34], N = 242). For women, we found a very weak effect in the opposite direction (d = −0.09, 95% CI [−0.30, 0.12], N = 360). The original studies may have overestimated the red effect, our studies may be an underestimate, or there could be strong moderation of the effect of red on attraction.

Comparison of Principal Component Solutions in Two Populations

Methodology ◽  
2016 ◽  
Vol 12 (1) ◽  
pp. 11-20 ◽  
Author(s):  
Gregor Sočan
Keyword(s):  
Simulation Study ◽  
Principal Components ◽  
Common Factor ◽  
Principal Component ◽  
Component Model ◽  
Bootstrap Procedure ◽  
Factor Loadings ◽  
Component Loadings ◽  
Principal Component Model ◽  
Two Populations

Abstract. When principal component solutions are compared across two groups, a question arises whether the extracted components have the same interpretation in both populations. The problem can be approached by testing null hypotheses stating that the congruence coefficients between pairs of vectors of component loadings are equal to 1. Chan, Leung, Chan, Ho, and Yung (1999) proposed a bootstrap procedure for testing the hypothesis of perfect congruence between vectors of common factor loadings. We demonstrate that the procedure by Chan et al. is both theoretically and empirically inadequate for the application on principal components. We propose a modification of their procedure, which constructs the resampling space according to the characteristics of the principal component model. The results of a simulation study show satisfactory empirical properties of the modified procedure.

Molecular phylogeny and taxonomic evaluation of the genus Asaccus Dixon and Anderson, 1973 (Reptilia: Phyllodactylidae) in Iran

2020 ◽  
pp. 207-214
Author(s):  
Akbar Fattahi
Keyword(s):  
Molecular Phylogeny ◽  
Nuclear Gene ◽  
Genetic Distances ◽  
Genetic Lineage ◽  
New Taxon ◽  
Zagros Mountains ◽  
Relict Species ◽  
Taxonomical Revision ◽  
Two Populations ◽  
Taxonomic Evaluation

The Iranian species of the phyllodactylid geckos of the genus Asaccus are found only in the valleys of the Zagros Mountains, a region which represents an important area of endemism in western Iran. Recently, many relict species have been described from the central and southern parts of the Zagros Mountains, which were previously known as A. elisae. The recent descriptions of species within this complex suggest that diversity within the genus may be higher than expected and that its taxonomy and systematics should be revised. In the present study, phylogenetic relationships within the genus Asaccus were evaluated using two mitochondrial and one nuclear gene. Genetically, the genus shows high levels of variability. The molecular phylogeny of the genus suggests the presence of three main clades along the Zagros Mountains with the southern population (from the Hormozgan province) and one clade (A. sp8 and A. sp9) being sister taxon to A. montanus from UAE. The remaining samples are separated into two reciprocally monophyletic groups: the northern (Kurdistan, Kermanshah and Ilam provinces) and the central (Lorestan, Khuzestan, Kohgilouye-Bouyer Ahmad and Fars provinces) Zagros groups. The results of the present study suggest that populations attributed to A. elisae in Iran correspond to distinct lineages with high genetic distances. In brief, our results suggest that the genus needs a major taxonomical revision The Arabian origin of the genus has not been confirmed, because two populations from Zagros were located within the A. montanus, A. gallagheri and A. platyrhynchus clade. Further morphological analyses are needed to systematically define each genetic lineage as a new taxon.

Comparing Genetic Variation within Red Winter Wheat Populations with and without Image-Based Optical Sorter Selection

2019 ◽  
Vol 9 (2) ◽  
pp. 266-277
Author(s):  
Hussein M. Khaeim ◽  
Anthony Clark ◽  
Tom Pearson ◽  
Dr. David Van Sanford
Keyword(s):  
Genetic Variation ◽  
Fusarium Head Blight ◽  
Heading Date ◽  
Fusarium Head Blight Resistance ◽  
Gibberella Zeae ◽  
Mass Selection ◽  
Head Blight ◽  
Red Winter Wheat ◽  
Two Populations ◽  
Head Scab

Head scab is historically a devastating disease affecting not just all classes of wheat but also barley and other small grains around the world. Fusarium head blight (FHB), or head scab, is caused most often by Fusarium graminearum (Schwabe), (sexual stage – Gibberella zeae) although several Fusarium spp. can cause the disease. This study was conducted to determine the effect of mass selection for FHB resistance using an image-based optical sorter. lines were derived from the C0 and C2 of two populations to compare genetic variation within populations with and without sorter selection. Our overall hypothesis is that sorting grain results in improved Fusarium head blight resistance. Both of the used wheat derived line populations have genetic variation, and population 1 has more than population 17. They are significantly different from each other for fusarium damged kernel (FDK), deoxynivalenol (DON), and other FHB traits. Although both populations are suitable to be grown for bulks, population 1 seems better since it has more genetic variation as well as lower FDK and DON, and earlier heading date. Lines within each population were significantly different and some lines in each population had significantly lower FDK and DON after selection using an optical sorter. Some lines had significant reduction in both FDK and DON, and some others had either FDK or DON reduction. Lines of population 1 that had significant reduction, were more numerous than in population 17, and FDK and DON reduction were greater.

An Implementation of a Remote Elder Care Support System using Bluetooth-based Motion Detectors

2016 ◽  
Vol 136 (2) ◽  
pp. 218-225
Author(s):  
Kyohei Sugino ◽  
Yusuke Niwa ◽  
Shun Shiramatsu ◽  
Tadachika Ozono ◽  
Toramatsu Shintani
Keyword(s):  
Support System ◽  
Elder Care ◽  
Motion Detectors ◽  
Care Support
Sign in / Sign up

Export Citation Format

Share Document