Anne L. Corn

Spatial and temporal limits of motion perception across variations in speed, eccentricity, and low vision

We evaluated spatial displacement and temporal duration thresholds for discriminating the motion direction of gratings for a broad range of speeds (0.06 degrees/s to 30 degrees/s) in fovea and at +/-30 degrees eccentricity. In general, increased speed yielded lower duration thresholds but higher displacement thresholds. In most conditions, these effects of speed were comparable in fovea and periphery, yielding relatively similar thresholds not correlated with decreased peripheral acuity. The noteworthy exceptions were interactive effects at slow speeds: (1) Displacement thresholds for peripheral motion were affected by acuity limits for speeds below 0.5 degrees/s. (2) Low-vision observers with congenital nystagmus had elevated thresholds for peripheral motion and slow foveal motion but resembled typically sighted observers for foveal motions at speeds above 1 degree/s. (3) Suppressive center-surround interactions were absent below 0.5 degrees/s and their strength increased with speed. Overall, these results indicate qualitatively different sensitivities to slow and fast motions. Thresholds for very slow motion are limited by spatial resolution, while thresholds for fast motion are probably limited by temporal resolution.

Peripheral Vision of Youths with Low Vision: Motion Perception, Crowding, and Visual Search

PURPOSE Effects of low vision on peripheral visual function are poorly understood, especially in children whose visual skills are still developing. The aim of this study was to measure both central and peripheral visual functions in youths with typical and low vision. Of specific interest was the extent to which measures of foveal function predict performance of peripheral tasks. METHODS We assessed central and peripheral visual functions in youths with typical vision (n = 7, ages 10-17) and low vision (n = 24, ages 9-18). Experimental measures used both static and moving stimuli and included visual crowding, visual search, motion acuity, motion direction discrimination, and multitarget motion comparison. RESULTS In most tasks, visual function was impaired in youths with low vision. Substantial differences, however, were found both between participant groups and, importantly, across different tasks within participant groups. Foveal visual acuity was a modest predictor of peripheral form vision and motion sensitivity in either the central or peripheral field. Despite exhibiting normal motion discriminations in fovea, motion sensitivity of youths with low vision deteriorated in the periphery. This contrasted with typically sighted participants, who showed improved motion sensitivity with increasing eccentricity. Visual search was greatly impaired in youths with low vision. CONCLUSIONS Our results reveal a complex pattern of visual deficits in peripheral vision and indicate a significant role of attentional mechanisms in observed impairments. These deficits were not adequately captured by measures of foveal function, arguing for the importance of independently assessing peripheral visual function.

Impact of optical devices on reading rates and expectations for visual functioning of school-age children and youth with low vision

Optical devices were prescribed and training provided for children with low vision in the state of Tennessee. Reading rates and comprehension rates were taken before introduction of the optical devices and after approximately six months of using the aids. Scores were also recorded of student, teacher, and parent expectations of the students’ visual functioning. Data show that students did not make significant changes in their silent or oral reading rates. However, it is important to note that they did make significant gains in comparison to the reading norms of their sighted peers. Data also show that expectation of students’ visual functioning increased in both students and their teachers. In contrast, parents’ expectations of students’ visual functioning decreased.

The Relationship Between Scores on the ICMIC and Selected Talent Domains: An Investigation With Gifted Adolescents

This investigation compared fantasy-proneness levels and IQ scores in gifted adolescents with primary talent areas in 1 of 4 domains: mathematics, computer science, creative writing, and chemistry. The Inventory of Childhood Memories and Imaginings: Children’s Form (ICMIC; Myers, 1983) was used to assess fantasy-proneness. IQ scores were generated through the Kaufman Brief Intelligence Test (K-BIT; Kaufman & Kaufman, 1990). The mean ICMIC score of the creative writing group was found to be statistically significantly higher than that of any of the other 3 groups. Across all groups, those ranking highest in fantasy-prone characteristics also scored highest in measured IQ.

A Collaborative Model for the Preparation of Teachers for Students with Visual Impairments.

There is a critical national shortage of teachers prepared to work with children who are blind and those with low vision. This article describes two federally funded projects that addressed the needs of school districts and specialized schools that were unable to locate and employ a teacher of students with visual disabilities. In the Collaborative Model 24 teacher-participants attended traditional on-campus programs 2 days per week while working in their local school districts, often hundreds of miles from campus, 3 days per week. Collaboration among educational agencies is described. Evaluations of the model using data from teacher-participants and school administrators is included along with costs for each project. Data indicate that the Collaborative-business Model is a viable, though more costly model for preparing teachers of students with a low incidence disability.