PubMed Health⌕ Search

Biomedical subjects

L A Lefton

Publications and source records attributed to L A Lefton.

7 recordsLinked to original sources
PubMed1980

Visual discrimination deficits of reading-disabled children: sex artifact?

Several theorists have suggested that deficits in visual discrimination play an etiological role in the development of reading deficits in children who are diagnosed as learning-disabled. Supporting this theory, a number of studies have shown that disabled readers make more errors on visual discrimination tasks than do good readers. The present study, however, suggests that those findings may have been due to a sex-difference artifact. Thirty-six 8- and 9-year-old good readers and reading-disabled children of both sexes responded to 40 matching items under untimed conditions. Males made more errors than females, but overall, reading-disabled children made no more errors than good readers. These findings, along with a reanalysis of previous studies, suggest that because reading disabilities are more common in males, evidence construed as supporting a visual discrimination hypothesis may have been an artifact of a sex difference in studies in which sex was not controlled.

Child↗
PubMed1977

Metacontrast as measured under a signal detection model.

Metacontrast is assessed both by percent accuracy and by the dichotomous sensitivity and criterion measures of a signal-detection model in a forced-choice detection task. The results showed a monotonic increase in sensitivity with increasing mask delay, and an abrupt shift of subjects' response criterion at an 80 ms interstimulus interval. The results are discussed in terms of the interpretational advantages of a signal-detection approach to metacontrast investigation.

Humans↗