Biomedical subjects
Publications and source records attributed to W Lovegrove.
Duration of visual persistance of sine-wave gratings of 1,2,4,8,12, and 16 cycles deg-1 was determined for seven-year-old, ten-year-old, and thirteen-year-old children. It was found that there was a decrease in persistence duration with age but the slope of this function for the different age groups did not change.
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The visual persistence of sinusoidal gratings of varying spatial frequency and contrast was measured. It was found that the persistence of low-contrast gratings was longer than that of high-contrast stimuli for all spatial frequencies investigated. At higher contrast levels of 1 and 4 cycles deg-1 gratings, a tendency for persistence to be independent of contrast was observed. For 12 cycles deg-1 gratings, however, persistence continued to decrease with increasing contrast. These results are compared with recently published data on other temporal responses, and are discussed in terms of the different properties of sustained and transient channels.
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Four experiments comparing the processing of contour orientation information in normal and specific reading disabled children were conducted. The first two experiments demonstrated that the reading disabled subjects had significantly longer visual information store durations than did the control subjects. In addition differences in visual information store durations for different orientations were found between the two groups. The final two experiments investigated processing of contour orientation information in the visual cortex. Results of Experiment IV suggested that the two groups differ in their processing of information in the visual cortex as well as in VIS. Because of the importance of feature detection in letter recognition, it is suggested that the present results may be important in understanding letter recognition is disabled readers.
8- and 11-yr-old reading-disabled children were compared in two experiments with controls matched on intelligence and age. Exp. 1 measured duration of visual information store by means of a separation threshold technique. Exp. II determined the rate of transfer from visual information store to short-term memory using a backward masking technique. Results from Exp. I showed that at each age specific reading-disabled children had significantly longer durations of visual information store than controls. The difference between the reading ability groups decreased with increasing age. Exp. II demonstrated that rate of transfer of information was significantly slower for specific reading-disabled children than for controls at both age levels. In contrast to Exp. I, this difference increased with increasing age. The results are considered in terms of their possible relevance to developmental lag theories. The evidence indicates that the development of visual information processing in reading-disabled children is similar to that in controls but occurs at a slower rate.
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