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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)
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)
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)
We quantified texture segregation by measuring psychophysically the percentage correct detection scores for each of a set of 10 texture-defined (TD) letters using the temporal two-alternative forced choice method, and at the same time quantified spatial discrimination of the TD form of measuring psychophysically the percentage correct letter recognition(More)
Exfoliated graphite (obtained by rapid heating of sulfuric-acid intercalated and subsequently deacidified graphite flakes) is optionally subjected to residual acidity removal, which involves repeated washing with water, such that the pH of the wash water increases from 2 to 7. Compared to washed exfoliated graphite, the unwashed material exhibits lower(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)
We quantified texture segregation by measuring psychophysically the percent correct detection scores for a set of 10 texture-defined (TD) letters using two-alternative forced-choice, and at the same time quantified spatial discrimination of TD form by measuring psychophysically the percent correct letter recognition scores for the 10 letters using(More)
During the past few years many researchers have attempted to find a psychophysical test that will identify at an early stage patients at risk for developing glaucoma. We investigated the ability of a test of motion-defined (MD) form recognition to discriminate between patients with primary open-angle glaucoma (POAG) and control subjects and to identify(More)