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Critical duration, contrast sensitivity, and specific reading disability


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Blackwood, Mary Heather 1979 , 'Critical duration, contrast sensitivity, and specific reading disability', Coursework Master thesis, University of Tasmania.

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Critical durations and contrast sensitivities for sine-wave
gratings of four different spatial frequencies - were measured in
normal and disabled readers. Two groups, each of ten subjects, with
an average age of 14 years, and matched as to seZ age; IQ, and
socio—economic status, were used. The results showed that while
critical duration for controls increases significantly with spatial
frequency, this is not so for disabled readers, suggesting that the
two groups may differ in terms of the temporal properties of their
spatial frequency channels. It Was also found, for stimulus durations
approximately equal to fixation durations, that disabled
readers were relatively less sensitive than were controls at low to
medium spatial frequencies. At all duration's there was a marked
contrast sensitivity loss at 4 c/deg. Controls, in respect of both
critical duration and contrast sensitivity function, produced results
similar to those found in other studies on normal adult subjects. The suggestion of spatial frequency-selective differences
in critical duration and the clear finding of such differences in
contrast sensitivity may indicate a fundamental abnormality in the
visual-temporal integration of spatial Stimuli. The existence of
such qualitative differences in children at this comparatively
mature age renders a developmental explanation unlikely. An explanation
discounting visual perceptual differences seems even more
untenable. The present study does not preclude a multi-factorial etiology
for SRD; it does; however, indicate that abnormality .in spatial
- frequency-specific channels of visual information processing is one
factor which can now confidently be included.

Item Type: Thesis - Coursework Master
Authors/Creators:Blackwood, Mary Heather
Keywords: Reading disability, Visual perception, Human information processing
Copyright Holders: The Author
Copyright Information:

Copyright 1979 the Author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s).

Additional Information:

Thesis (M. Psych.) - University of Tasmania, 1980. Bibliography: l. 83-89

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