scholarly journals A horse's eye view: size and shape discrimination compared with other mammals

2015 ◽  
Vol 11 (11) ◽  
pp. 20150701 ◽  
Author(s):  
Masaki Tomonaga ◽  
Kiyonori Kumazaki ◽  
Florine Camus ◽  
Sophie Nicod ◽  
Carlos Pereira ◽  
...  
Keyword(s):  
Visual Acuity ◽  
Cognitive Abilities ◽  
Visual Discrimination ◽  
Natural Environments ◽  
Perceptual Similarity ◽  
Shape Discrimination ◽  
Size And Shape ◽  
Circle Size ◽  
Computer Controlled

Mammals have adapted to a variety of natural environments from underwater to aerial and these different adaptations have affected their specific perceptive and cognitive abilities. This study used a computer-controlled touchscreen system to examine the visual discrimination abilities of horses, particularly regarding size and shape, and compared the results with those from chimpanzee, human and dolphin studies. Horses were able to discriminate a difference of 14% in circle size but showed worse discrimination thresholds than chimpanzees and humans; these differences cannot be explained by visual acuity. Furthermore, the present findings indicate that all species use length cues rather than area cues to discriminate size. In terms of shape discrimination, horses exhibited perceptual similarities among shapes with curvatures, vertical/horizontal lines and diagonal lines, and the relative contributions of each feature to perceptual similarity in horses differed from those for chimpanzees, humans and dolphins. Horses pay more attention to local components than to global shapes.

An Exploratory Study of Mirror-Image Shape Discrimination in Young Children: Vision and Touch

1994 ◽  
Vol 78 (1) ◽  
pp. 83-88 ◽  
Author(s):  
Shoji Itakura ◽  
Hiroshi Imamizu
Keyword(s):  
Young Children ◽  
Shape Analysis ◽  
Visual Discrimination ◽  
Exploratory Study ◽  
Mirror Image ◽  
Shape Discrimination ◽  
Relative Dominance ◽  
English Alphabet ◽  
Image Shape

30 children (18 boys and 12 girls) with a mean age of 4 yr., 8 mo. were subjects in an experiment testing the relative dominance of visual and tactual modalities in mirror-image shape discrimination. The sets of unfamiliar stimuli (written and wooden letters of the English alphabet, P, B, C, U, R, F) were presented to the children randomly. Children matched the stimulus with either another visual or another tactual shape. Analysis suggests touch is not inferior to vision in mirror-image shape discrimination. These results are different from those of previous reports comparing tactual and visual discrimination with nonmirror-image patterns.

scholarly journals The influence of size and shape of Nd:YAG capsulotomy on visual acuity and refraction

2015 ◽  
Vol 78 (4) ◽  
pp. 220-223 ◽  
Author(s):  
Servet Cetinkaya ◽  
Yasemin Fatma Cetinkaya ◽  
Halil Ibrahim Yener ◽  
Zeynep Dadaci ◽  
Muammer Ozcimen ◽  
...  
Keyword(s):  
Visual Acuity ◽  
Size And Shape

scholarly journals Large Amounts of Optical Blur Greatly Reduce Visual Acuity but Have Minimal Impacts upon 3-D Shape Discrimination

2010 ◽  
Vol 10 (7) ◽  
pp. 72-72
Author(s):  
A. Beers ◽  
J. F. Norman ◽  
J. Swindle ◽  
A. Boswell
Keyword(s):  
Visual Acuity ◽  
Shape Discrimination ◽  
Optical Blur

scholarly journals Towards a new understanding of fear generalization and its neural origin

2018 ◽  
Author(s):  
Selim Onat
Keyword(s):  
Anxiety Disorders ◽  
Cognitive Abilities ◽  
Conceptual Knowledge ◽  
Brain Structures ◽  
Perceptual Similarity ◽  
Inference Problem ◽  
Complex Skill ◽  
Complex Adaptive ◽  
Neural Origin ◽  
Fear Generalization

Forming generalizations from previous experiences is a complex skill, which requires a delicate coordination between several basic cognitive abilities. In menacing situations, this ability is called “fear generalization”. It allows humans to predict harmful events and is necessary for survival. Impairments of this ability may lead to overgeneralizations – a phenomenon we know from anxiety disorders. By and large, fear generalization has been studied with one type of experimental paradigm. Stimuli forming a carefully controlled perceptual similarity gradient have been the basis to quantify behavioral and neuronal “fear generalization profiles”. This paradigm has provided fruitful insights into how learnt fear generalizes to perceptually similar events. Yet, a number of findings suggest that fear generalization is more adaptive than predicted by a mechanism which is solely based on perceptual similarity. This is a proposal that aims to bring new perspectives onto fear generalization as a complex, adaptive process. I will investigate the following major hypotheses: (1) Fear generalization can be understood as the optimal result of a Bayesian inference problem. (2) In real-world conditions, fear generalization builds on conceptual knowledge rather than perceptual similarity alone. (3) Brain structures involved in fear generalization can be causally linked to modulate fear responses adaptively. To test these hypotheses, I propose use of tools including fMRI, EEG as well as intracranial electrical stimulation and LFP recordings in presurgical epilepsy patients. With the combination of these tools, the expected findings have the potential to revolutionize our understanding of fear generalization and anxiety disorders.

scholarly journals Cleaner wrasse indirectly affect the cognitive performance of a damselfish through ectoparasite removal

2018 ◽  
Vol 285 (1874) ◽  
pp. 20172447 ◽  
Author(s):  
Sandra A. Binning ◽  
Dominique G. Roche ◽  
Alexandra S. Grutter ◽  
Simona Colosio ◽  
Derek Sun ◽  
...  
Keyword(s):  
Cognitive Abilities ◽  
Visual Discrimination ◽  
Negative Impact ◽  
Cognitive Impairments ◽  
Discrimination Performance ◽  
Innate Immune ◽  
Discrimination Test ◽  
Pomacentrus Amboinensis ◽  
Spatial Recognition

Cleaning organisms play a fundamental ecological role by removing ectoparasites and infected tissue from client surfaces. We used the well-studied cleaning mutualisms involving the cleaner wrasse, Labroides dimidiatus, to test how client cognition is affected by ectoparasites and whether these effects are mitigated by cleaners. Ambon damselfish ( Pomacentrus amboinensis) collected from experimental reef patches without cleaner wrasse performed worse in a visual discrimination test than conspecifics from patches with cleaners. Endoparasite abundance also negatively influenced success in this test. Visual discrimination performance was also impaired in damselfish experimentally infected with gnathiid (Crustacea: Isopoda) ectoparasites. Neither cleaner absence nor gnathiid infection affected performance in spatial recognition or reversal learning tests. Injection with immune-stimulating lipopolysaccharide did not affect visual discrimination performance relative to saline-injected controls, suggesting that cognitive impairments are not due to an innate immune response. Our results highlight the complex, indirect role of cleaning organisms in promoting the health of their clients via ectoparasite removal and emphasize the negative impact of parasites on host's cognitive abilities.

scholarly journals ON THE VARIABILITY OF CRITICAL ILLUMINATION FOR FLICKER FUSION AND INTENSITY DISCRIMINATION

1936 ◽  
Vol 19 (3) ◽  
pp. 503-522 ◽  
Author(s):  
W. J. Crozier
Keyword(s):  
Visual Acuity ◽  
General Problem ◽  
Visual Function ◽  
Visual Discrimination ◽  
Dark Adaptation ◽  
Intensity Discrimination ◽  
The Sun ◽  
Threshold Response ◽  
Independent Variable ◽  
Flicker Fusion

From the data of experiments with bees in which threshold response is employed as a means of recognizing visual discrimination between stripes of equal width alternately illuminated by intensities I1 and I2, it is shown that the detectable increment of intensity ΔI, where ΔI = I2 - I1, is directly proportional to σI2 (I1 being fixed). From tests of visual acuity, where I1 = 0 and the width of the stripes is varied, σI2 = kI2 + const.; here I2 = ΔI, and ΔI/I2 = 1. When the visual excitability of the bee is changed by dark adaptation, λI ≡ kΔI (= k' σΔI) = k'' I + const. For the measurements of critical illumination at threshold response to flicker, σI2 (= σΔI) = k I2 = k' ΔI + const. The data for critical illumination producing threshold response to flicker in the sun-fish Lepomis show for the rods σI2 = K I2 for the cones σI2 = K'(I2 + const.). The data thus indicate that in all these experiments essentially the same visual function is being examined, and that the recognition of the production of a difference in effect by alternately illuminated stripes takes place in such a way that d (ΔI)/d (σI2) = const., and that ΔI is directly proportional to I (or "I2," depending on the nature of the experiment). It is pointed out that the curve for each of the cases considered can be gotten equally well if mean I or σI is plotted as a function of the independent variable involved in the experiment. Certain consequences of these and related facts are important for the treatment of the general problem of intensity discrimination.

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