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The following psychophysical data were obtained from 13 patients with unilateral cerebral hemispheric lesions and 20 control subjects: speed thresholds for detecting and for recognizing motion-defined letters, speed thresholds for detecting coherent motion and for discriminating its direction, and visual acuity for recognizing letters of 96% and 11%(More)
The following three measurements were made on a group of 20 pediatric and 5 adult patients with unilateral amblyopia: (1) speed threshold for recognizing motion-defined dotted letters; (2) recognition acuity for isolated solid letters of 4% contrast; and (3) Snellen line acuity for high-contrast letters. Normal limits were established with a group of 30(More)
There are several visual mechanisms for analyzing spatial information additional to the much researched mechanism sensitive to luminance contrast. We describe a Snellen-type acuity test for motion-defined (MD) letters. Acuity for these MD letters collapsed at dot speeds slower than 0.05 deg/s, but acuity for contrast-defined (CD) letters was unaffected by(More)
A pattern of 12,860 short (0.15 x 0.05 deg) texture lines contained an orientation texture-defined (OTD) rectangle of aspect ratio a/b (a was the rectangle's height and b was its width). All the lines within the rectangle had the same orientation and all the lines outside the rectangle had the same orientation. These two orientations were theta deg(More)
Two important distinctions in visual perception are (1) between the detection and recognition of shape (e.g., letters), and (2) between the recognition of shapes defined by a difference in brightness and the recognition of shapes defined by a difference in motion. We report that 6 of 10 patients with multiple sclerosis showed impaired recognition for(More)
Visual fields for oscillatory motion in depth were recorded for 21 subjects. Near fields were different from far fields in 8 and similar in 11 subjects. Visual fields for unidirectional motion in depth were recorded for 16 subjects for near and far disparities. Some subjects had fields that differed for approaching versus receding motion in depth and/or for(More)
This study aims to identify the landscape ecological determinants related to Oncomelania hupensis distribution, map the potential high risk of O. hupensis habitats at the microscale, and assess the effects of two environmental control strategies. Sampling was performed on 242 snail sites and 726 non-snail sites throughout Qianjiang City, Hubei Province,(More)
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