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Biomedical subjects

E Chekaluk

Publications and source records attributed to E Chekaluk.

5 recordsLinked to original sources
PubMed1998

The effects of visual discomfort and pattern structure on visual search.

Unpleasant somatic and perceptual side effects can be induced when viewing striped repetitive patterns, such as a square wave or a page of text. This sensitivity is greater in participants with higher scores on a scale of visual discomfort. In three experiments the effect that this sensitivity has on performance efficiency in a reading-like visual search task was investigated. In experiments 1 and 2, the 'global' structure of the patterns was manipulated to produce a square-wave, a checkerboard, and a plaid pattern. It was found that the group that suffered severe visual discomfort took significantly longer than other groups to perform the task, with interference greatest with presentation of the square-wave-like pattern. This supports the prediction of greatest distraction of visual attention from the local target elements with presentation of the pattern structure inducing greatest visual discomfort. In experiment 3, the internal pattern components were manipulated and task difficulty reduced. A no-interference and two interference patterns, one with a global characteristic only and the second made up of distracting line elements, containing global and local components were used. The global pattern structure produced interference effects on the visual-search task. All groups performed with the same speed and accuracy on the task involving the no-interference pattern, a finding attributed to reduced task difficulty. McConkie and Zola's model of visual attention was used to explain these results.

Asthenopia↗
PubMed1993

Early reading performance: a comparison of teacher-based and test-based assessments.

An unresolved question in early screening is whether test-based or teacher-based assessments should form the basis of the classification of children at risk of educational failure. Available structured teacher rating scales are lacking in predictive validity, and teacher predictions of students likely to experience reading difficulties have yielded disappointing true positive rates, with teachers failing to identify the majority of severely disabled readers. For this study, three educational screening instruments were developed: (a) a single teacher rating, categorizing children into three levels of reading ability (advanced, average, poor); (b) a 15-item teacher questionnaire designed to measure students' cognitive and language ability, attentional and behavioral characteristics, and academic performance; and (c) a battery of language and reading tests that are predictive of, or correlate with, reading failure. The concurrent validity of each instrument was assessed in a sample of 312 Australian schoolchildren from kindergarten, Year 1, and Year 2. Students were assessed at the end of the 1989 school year after having completed 1, 2, or 3 years of schooling. The results suggest that the nature of the skills required for success in reading changes in the first 3 years of schooling. Both teachers and tests concur more closely as children progress through the elementary years and as the risk behavior (reading) becomes more accessible to direct measurement. Carefully focused teacher rating scales may be a cost-effective means of identifying children at risk of reading failure. Improved teacher rating scales should be developed and used to assist in the early screening process.

Child↗
PubMed1991

Academic performance of mature-age and other students in a physiotherapy program.

Students enrolled in the physiotherapy undergraduate program of the University of Sydney comprise school leavers (students who have completed secondary school-category A) and non-school leavers (category B), including mature-age students (23 years and older). Student selection is based upon academic performance (categories A and B) and personal interview (category B only). Statistical evaluations of the academic performance of 799 students who commenced the undergraduate course between 1982 and 1986 revealed a) no significant difference between the time taken to complete the undergraduate program; b) in 26 of 31 compulsory subjects, category A and category B students performed equally well; in one subject category, B students performed significantly better; in three subjects, the mature-age students performed significantly better; and only in one subject did mature-age students perform less well; c) no difference in the academic performance of male and female students; d) the Higher School Certificate aggregate provided a poor to moderate indicator of academic performance. The results justify both the reservation of places offered to nonschool leavers and the system used for their selection.

Achievement↗
PubMed1990

Visual stimulus input, saccadic suppression, and detection of information from the postsaccade scene.

Tachistoscopic presentation of saccadic stimulus sequences to fixating subjects produced saccadic suppression curves only when the pre- and postsaccade fixation fields were structured. Displacement in the sense either of movement of the intrasaccade display or of change from pre- to postsaccade fixation field was not required. Variation of intrasaccade displays from contours moving at saccadic rates to a stationary gray field had no effect. When one structured field immediately followed another, the change of sensitivity mimicked suppression, but an interposed grayout magnified the loss and therefore probably reduced carryover from the first fixation field. Interposed grayout also delayed recovery but reduced the latency of detection of information from the postfield, so that it appears to have reduced stimulus overload from the sudden presentation of the second field.

Adult↗