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Biomedical subjects

L E Ross

Publications and source records attributed to L E Ross.

At least 37 records · Page 2Linked to original sources
PubMed1984

Comparison scan training and the matching and scanning performance of severely and profoundly mentally retarded students.

This study investigated the effects of comparison scan training on the matching and visual scanning performance of severely and profoundly mentally retarded students. A match-to-sample-problem pretest was administered to 32 students, whose eye movements were recorded on videotape, and the 12 subjects who demonstrated at least minimal competence on the pretest task were matched on pretest performance and assigned to training (n = 6) or comparison (n = 6) groups. Training-group students were provided with visual comparison scan training, while the comparison group performed the same task but received no training. A posttest identical to the pretest followed. The training group was superior to the comparison group during training and showed a significant increase in correct responding from pretest to posttest, whereas the comparison group did not. Neither measures of scanning behavior nor the latencies of the choice response were related to matching performance or affected by the training procedure. Possible relationships among visual scanning, comparison scan training, and matching-task performance were discussed.

Discrimination Learning↗
PubMed1983

The effects of onset and offset warning and post-target stimuli on the saccade latency of children and adults.

Two studies, involving children (mean age = 10 years) and adults, investigated the effects of visual stimulus onsets and offsets on the latency of saccades to peripheral targets. Saccade latency was reduced when foveal stimulus onsets or offsets preceded the target. When stimulus onset occurred 100 msec after target onset, the stimulus interfered with responding, with this interference effect significantly greater for children than for adults. When stimuli were presented in the peripheral visual field facilitation and interference effects were similar for children and adults. These results were interpreted as indicating that oculomotor processes are similar in children and adults while the stimulus intake processes that follow stimulus onset at the point of fixation have a greater interference effect on children's than on adults' eye movements.

Adult↗
PubMed1977

Warning signals and alerting: effects on differential classical conditioning.

Three experiments were carried out to investigate the effects of a nondifferential warning signal on differential classical conditioning. In Experiment 1, a 500-msec warning interval was found to result in good differential conditioning performance at an interstimulus interval (ISI) of 500 msec in which differential conditioning did not otherwise occur. The second experiment demonstrated the warning effect with both visual and auditory conditioned stimuli, thus ruling out the possibility that the warning effects were due to eye movements. Experment 3 showed that a warning signal and an increased ISI were functionally equivalent, as demonstrated by conditioning performance and the similar effects obtained when the ISI and warning-interval conditions were switched from optimal to nonoptimal and vice versa.

Acoustic Stimulation↗
PubMed1975

Severely retarded children as impulsive responders: improved performance with response delay.

A community school-project class of 15 severely retarded children showed a high negative relationship between errors and response latency (r = -.92) when tested on a task which required selection of the one of six line drawings that matched a standard. Fast incorrect (impulsive) responders on the matching task had previously been unsuccessful in receptive-language color discrimination training while slow correct (reflective) responders had been successful on the same task. The four most impulsive responders were given additional color discrimination training for an extended period under conditions where (a) a response could be made immediately (no-delay) or (b) a 5-second delay was imposed between presentation of the stimuli and the opportunity to respond (delay). Performance of all four children was at chance levels during periods of no-delay trials, but high performance levels (80 to 90 percent correct) were achieved when delay trials were given. Upon changing from delay to no-delay, subjects' performance again fell to chance levels. Implications for training programs were discussed.

Adolescent↗
PubMed1975

Stimulus input recruitment and stimulus trace decay factors in the trace conditioning deficit of severely retarded young adults.

Trace and delay classical eyelid conditioning procedures were used to investigate the relative contributions of conditioned stimulus input recruitment and trace decay processes to the trace conditioning deficit of severely and profoundly retarded subjects. The study included both trace and delay conditioning groups at interstimulus intervals of 500 and 950 msec. The conditioned stimulus durations were 50 msec for the 500-msec interstimulus interval trace group and 500 msec for the 950-msec interstimulus interval trace group. The "empty" interval between conditioned stimulus offset and the onset of the unconditioned stimulus was 450 msec for both trace conditioning groups. After 250 conditioning trials, there was no difference between the two trace groups, and both were significantly below the delay groups in final level of responding. These results suggest that stimulus trace decay rather than input recruitment, as manipulated by varying conditioned stimulus duration, accounts for the poor trace conditioning performance demonstrated by these subjects.

Adolescent↗