Real and Subjective Contour Poggendorff Illusions: No Differences Based on Eye Color

Perception ◽  
1988 ◽  
Vol 17 (3) ◽  
pp. 311-313 ◽  
Author(s):  
Peter A Beckett ◽  
Stephen Hurajt
Keyword(s):  
Subjective Contour ◽  
Illusion Magnitude ◽  
Eye Color ◽  
Real Contour ◽  
Type Variable ◽  
Iris Pigmentation ◽  
Figure Type

Measures of illusion magnitude for a real contour and two subjective contour Poggendorff figures were obtained from a large number of dark-eyed and light-eyed undergraduates. Illusion magnitude varied as a function of figure type. However, eye color neither had a significant overall effect on illusion magnitude, nor did it interact with the figure-type variable. These data indicate that the presence of intersecting lines is not the basis of the iris-pigmentation effect reported by Coren and Porac.

Iris Pigmentation and Visual-Geometric Illusions

Perception ◽  
1978 ◽  
Vol 7 (4) ◽  
pp. 473-477 ◽  
Author(s):  
Stanley Coren ◽  
Clare Porac
Keyword(s):  
Retinal Image ◽  
Scattered Light ◽  
Illusion Magnitude ◽  
Ebbinghaus Illusion ◽  
Image Degradation ◽  
Lyer Illusion ◽  
Iris Pigmentation ◽  
Line Elements

Blur or degrading of the retinal image has been shown to be a factor in the formation of visual-geometric illusions where intersecting line elements are present. Light irises allow more scattered light within the eye, which results in more image degradation than found in dark-eyed subjects. Measurements on 755 observers show that illusion magnitude varies as a function of iris pigmentation for a configuration with intersecting line elements (Müller — Lyer illusion), but not for a configuration devoid of such features (Ebbinghaus illusion).

Eye Color and Feeding Behavior of Animals

1991 ◽  
Vol 73 (3) ◽  
pp. 1033-1034 ◽  
Author(s):  
Morgan Worthy
Keyword(s):  
Feeding Behavior ◽  
Systematic Relationship ◽  
Eye Color ◽  
Iris Pigmentation ◽  
Land Vertebrates

A theory is presented of a systematic relationship between iris pigmentation and feeding behavior of land vertebrates.

Psychophysical evidence for area V2 involvement in the reduction of subjective contour tilt aftereffects by binocular rivalry

1994 ◽  
Vol 11 (4) ◽  
pp. 823-830 ◽  
Author(s):  
Rick van der Zwan ◽  
Peter Wenderoth
Keyword(s):  
Binocular Rivalry ◽  
Subjective Contour ◽  
Visual Pathway ◽  
Two Stage ◽  
Area V2 ◽  
Real Contour ◽  
Stage Process

AbstractPrevious research suggests binocular rivalry disrupts extrastriate, but not striate processes, although the locus along the visual pathway at which such disruption first occurs is uncertain. It has been argued that subjective contours arise via a two-stage process in which end-stopped cells feed into orientation-sensitive neurones in V2, and that orientation aftereffects induced with subjective contours are the product of mechanisms similar to those giving rise to real contour aftereffects. If binocular rivalry disrupts the acquisition of subjective contour aftereffects, then it follows from this model that rivalry disrupts processing in V2. Experiments reported here confirm this and provide evidence which suggests binocular rivalry arises through interactions between binocular neurones, rather than via some type of specialized binocular rivalry mechanism.

Human Eye Color and Reaction Time

1978 ◽  
Vol 47 (2) ◽  
pp. 503-506 ◽  
Author(s):  
W. H. Tedford ◽  
W. R. Hill ◽  
Lynn Hensley
Keyword(s):  
Reaction Time ◽  
Visual Stimulus ◽  
Reaction Times ◽  
Nonsignificant Trend ◽  
Response Latencies ◽  
Eye Color ◽  
Human Eye ◽  
Trend Data ◽  
Iris Pigmentation ◽  
Reaction Task

Response latencies to a visual stimulus were determined for 44 male and 82 female Caucasians. Those with dark eyes had significantly shorter simple (one stimulus) reaction times. Complex (one of four stimuli) reaction times showed a similar, but nonsignificant, trend. Data from an additional 206 male Caucasians on a one-trial non-practiced reaction task followed the same nonsignificant trend. Darker iris pigmentation apparently correlates with shorter reaction times but more strongly on practiced tasks and on those which do not involve accuracy.

scholarly journals HERC2 and OCA2 genes polimorphisms in relation to the iris color variation of the Belarusian population

2021 ◽  
Vol 65 (1) ◽  
pp. 59-67
Author(s):  
M. N. Shapturenko ◽  
A. V. Kondratiuk ◽  
S. I. Vakula ◽  
M. V. Seredenko (Shinkevich) ◽  
I. G. Gudzievskaya ◽  
...  
Keyword(s):  
High Efficiency ◽  
Forensic Genetics ◽  
Color Variation ◽  
Taqman Assay ◽  
Nucleotide Polymorphisms ◽  
Cumulative Impact ◽  
Eye Color ◽  
Iris Color ◽  
Iris Pigmentation ◽  
Developing Area

The human genetic phenotyping is one of the most intensely developing area of forensic genetics. Externally visible traits, including eye color, can be predicted by analyzing single nucleotide polymorphisms with a high predictive rate. We studied the polymorphisms rs12913832 and rs1800407 in the HERC2 and OCA2 genes, respectively, to evaluate its prognostic availability in relation to the iris pigmentation of the Belarusian population. For this, both eye images and DNA samples were collected from 314 individuals to analyze the key polymorphisms by the TaqMan assay. Our data confirmed a relevance of rs12913832:A>G and rs1800407:G>A in the prediction context. The highest values of the sensitivity (SE = 0.94) and the specificity (SP = 0.90) were obtained for rs12913832, demonstrating the high efficiency of this marker as a classifier of phenotypic groups. The presence of the ancestral dominant allele rs12913832-A causes a dark (brown) iris pigmentation, how- ever, the heterozygous state rs12913832:GA includes a range of mixed variants. The predictive value of rs1800407 for the genetic phenotyping is highly significant (SE = 0.98), but has a low specificity (SP = 0.14), thus rs1800407, not being an effective classifier, can be used as an auxiliary in the eye color predictive model. The analysis of a cumulative impact of the both poly- morphisms on the iris color variation shows their high prospects for the genetic phenotyping of the Belarusian population.

The Horizontal-Vertical Illusion and Knowledge of Results

1988 ◽  
Vol 67 (2) ◽  
pp. 463-469 ◽  
Author(s):  
Gary M. Brosvic ◽  
Beth D. Cohen
Keyword(s):  
Horizontal Plane ◽  
Vertical Plane ◽  
Illusion Magnitude ◽  
Line Bisection ◽  
Vertical Line ◽  
Comparison Line ◽  
Knowledge Of Results ◽  
Control Subjects ◽  
Figure Type

The Horizontal-Vertical (HV) Illusion was examined in two studies in which subjects adjusted the vertical line in L-shaped and inverted-T figures or produced lines in the vertical and horizontal planes. On the adjustment tasks, vertical lines were made significantly shorter than horizontal comparison lines, especially for the inverted-T figure. On the production tasks, lines drawn in the vertical plane were significantly shorter than lines drawn in the horizontal plane. The adjusted and created lines of subjects receiving intertrial feedback on illusion magnitude were significantly more accurate and less variable than the estimations of control subjects. Performance on either task or figure type did not differ as a function of sex of subject. The present results show that the HV illusion exists in the absence of line bisection or a comparison line and results from the overestimation of vertical lines. These findings further clarify the relative contributions of the structural and strategy mechanisms in the formation of the Horizontal-Vertical Illusion.

scholarly journals An extensive photometric study of the Blazhko RR Lyrae star RZ Lyr*

2012 ◽  
Vol 423 (2) ◽  
pp. 993-1005 ◽  
Author(s):  
J. Jurcsik ◽  
Á. Sódor ◽  
G. Hajdu ◽  
B. Szeidl ◽  
Á. Dózsa ◽  
...  
Keyword(s):  
Light Curve ◽  
Light Curves ◽  
Stellar Structure ◽  
Time Base ◽  
Photometric Method ◽  
Physical Parameters ◽  
Component Solution ◽  
Rr Lyrae ◽  
Curve Variation ◽  
Type Variable

Abstract The analysis of recent, extended multicolour CCD and archive photoelectric, photographic and visual observations has revealed several important properties of RZ Lyr, an RRab-type variable exhibiting large-amplitude Blazhko modulation. On the time base of ∼110 yr, a strict anticorrelation between the pulsation- and modulation-period changes is established. The light curve of RZ Lyr shows a remarkable bump on the descending branch in the small-amplitude phase of the modulation, similarly to the light curves of bump Cepheids. We speculate that the stellar structure temporally suits a 4:1 resonance between the periods of the fundamental and one of the higher order radial modes in this modulation phase. The light-curve variation of RZ Lyr can be correctly fitted with a two-modulation-component solution; the 121-d period of the main modulation is nearly but not exactly four times longer than the period of the secondary modulation component. Using the inverse photometric method, the variations in the pulsation-averaged values of the physical parameters in different phases of both modulation components are determined.

Association of Eye Color and Sex with Basketball Free Throws by Elementary School Children

1991 ◽  
Vol 73 (3_suppl) ◽  
pp. 1181-1182
Author(s):  
Tammy Patee ◽  
Mike Frewen ◽  
John Beer
Keyword(s):  
High School ◽  
Elementary School ◽  
School Children ◽  
Elementary School Children ◽  
Eye Color ◽  
Free Throw

Dark-eyed individuals perform reactive activities better while light-eyed individuals generally perform self-paced activities better. There were 68 (21 dark-and 47 light-eyed) elementary school children who shot 5 practice and then 15 free throws from the free-throw line in a high school gym. There were no differences in performance between light- and dark-eyed children, but boys scored more free throws than girls.

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