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Biomedical subjects

K L Shapiro

Publications and source records attributed to K L Shapiro.

8 recordsLinked to original sources
PubMed1992

Temporary suppression of visual processing in an RSVP task: an attentional blink? .

Through rapid serial visual presentation (RSVP), we asked Ss to identify a partially specified letter (target) and then to detect the presence or absence of a fully specified letter (probe). Whereas targets are accurately identified, probes are poorly detected when they are presented during a 270-ms interval beginning 180 ms after the target. Probes presented immediately after the target or later in the RSVP stream are accurately detected. This temporary reduction in probe detection was not found in conditions in which a brief blank interval followed the target or Ss were not required to identify the target. The data suggest that the presentation of stimuli after the target but before target-identification processes are complete produces interference at a letter-recognition stage. This interference may cause the temporary suppression of visual attention mechanisms observed in the present study.

Adult↗
PubMed1990

Temporal processing in dyslexia.

The temporal processing capabilities of 15 children with dyslexia versus 15 age-matched and 15 reading-matched controls in a word identification task were examined. The hypothesis underlying the present experiment was that word recognition would be inferior in children with dyslexia, relative to controls, when the task demanded the temporal integration (sequencing) of two-syllable words. Such a hypothesis must predict that one-syllable word recognition does not distinguish between these two populations and that these effects cannot be accounted for in terms of eye movement differences. To test this hypothesis, one- and two-syllable words displayed for 100, 300, and 3,000 msec were required to be identified. The results yielded evidence of decreased accuracy of word identification by the children with dyslexia in the two-syllable, 300-msec condition, as predicted. A second experiment was unable to uncover any differences in eye movement behaviors that could account for the effects observed in the first experiment. The results are discussed in terms of potential sequential processing deficits in individuals with dyslexia.

Adolescent↗
PubMed1989

Training of efficient oculomotor strategies enhances skill acquisition.

The present study investigated the hypothesis that efficient oculomotor behaviours can be acquired through practice on a series of simple tasks and can be transferred subsequently to a complex visuomotor task, such as a video game. Each of two groups of subjects were exposed to a different set of simple tasks, or drills. One group, the efficient eye movement experimental group, received training designed to minimize eye movements and optimize scan path behaviours, whereas a second group of subjects, the inefficient eye movement experimental group, received training designed to increase the frequency of eye movements. Oculomotor training was interspersed with practice on the video game. Performance of these two experimental groups in the video game was compared to a control group playing the video game but receiving no specific training and matched for total time in the experiment. The group receiving efficient oculomotor training exhibited significantly superior performance in the video game and fewer foveations than either the inefficient or control groups, which did not differ from each other. Overall there was a significant inverse correlation between the number of foveations in the game and game score. The results of this study are discussed in terms of their implications for the importance of oculomotor training in the acquisition of any complex perceptual motor task.

Adolescent↗
PubMed1989

Attention to auditory and peripheral visual stimuli: effects of arousal and predictability.

Changes in the distribution of attention among auditory and peripheral visual stimuli were examined in a choice reaction time paradigm. Two variables were manipulated: predictability of stimulus locations and arousal state of subjects. The arousal level of some subjects was raised by occasionally exposing them to brief, mild electric shocks. On most trials either a tone or a light was presented alone (single-stimulus trials). However, on 20% of the trials both a tone and light were presented simultaneously (dual trials). Two dependent variables were used to assess dominance of attention: reaction time (on all trials) and percentage of time each modality was chosen on dual trials. Neither modality was dominant when subjects were in a nonaroused state and stimulus locations were unpredictable. However, peripheral vision dominated when stimulus locations were predictable or when the subjects' level of arousal was raised. The results are discussed with reference to previous research on sensory dominance and on the facilitating or inhibiting effects of auditory stimuli on reaction time.

Adolescent↗
PubMed1989

The impact of anxiety on visual attention to central and peripheral events.

Recent reports in the literature suggest that anxious individuals show an attentional bias to mood-congruent information. Various investigators have hypothesized that such anxiety-based coding biases contribute to the maintenance of mood disorders. The present study sought to determine if attentional biases in anxious subjects extends to the perception of neutral, as opposed to affect-laden, stimuli. A procedure used to determine the locus of attention to foveal and peripheral visual events was used in combination with two inter-stimulus intervals, fixed and variable, to examine anxious and non-anxious subjects' attentional biases. Mood states were established by a well-validated musical induction procedure. The results revealed an attentional bias to foveal visual events in non-anxious subjects and an attenuated or reversed (peripheral) bias in anxious subjects. The clinical implications of these findings are discussed.

Adolescent↗
PubMed1988

Usefulness of computerized visual acuity testing in a pediatric ophthalmology clinic.

We investigated the usefulness of a computerized illiterate-E-style acuity test in 111 children ranging in age from 3 to 13 (mean 6.56) years consecutively referred to a large pediatric ophthalmology clinic. Visual acuity was measured in both eyes of each subject by means of conventional testing with an optical projection device and computerized testing with a program run on a microcomputer. Of the 222 eyes 155 (70%) showed no difference in visual acuity between the two procedures. A difference of one acuity line was found for 63 eyes (28%), and a difference of two lines was found for 4 eyes (2%). The conventional test yielded a higher acuity score in 75% of the cases in which a one-line difference was found and 50% of those in which a two-line difference was found. Our results indicate that computerized testing is a valid and effective method of assessing visual acuity in children.

Adolescent↗