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Biomedical subjects

J Morais

Publications and source records attributed to J Morais.

At least 73 records · Page 4Linked to original sources
PubMed1987

Ear differences in illiterates.

The influence of literacy on direction and magnitude of ear asymmetry was assessed using the dichotic technique with three groups of adult females: illiterates, semiliterates and literates. Subjects were presented pairs of CVCV words which differed either in the initial consonant only, or in at least the first three phones. Their task was to report the word heard at the attended ear. A right ear advantage was observed in all groups; it was of roughly the same magnitude for the dissimilar pairs; for the similar ones, the laterality index was greater in the literates. However, an analysis of individual data showed that this difference was related to differences in performance level. When subgroups of similar performance level were compared, no differences in right ear advantage were found as a function of literacy.

Adult↗
PubMed1987

Analytic processing in the classification of melodies as same or different.

Two groups of non-musicians were required to classify pairs of melodies as "same" or "different". The experimental group was instructed to respond as fast as possible, while the control group did not receive such a speed requirement. Contrary to the control subjects, the experimental subjects exhibited a right-ear advantage in accuracy for "different" responses. Thus, time pressure was instrumental in inducing subjects to rely mainly on left-hemisphere processing. The fact that "different" responses were both faster than "same" ones and quicker than melody offset indicates the use of a self-terminating search process. The features searched for were, in all likelihood, local. Indeed, contrary to control subjects, experimental subjects performed equally well with (1) melodies differing in both contour and local pitches and with (2) melodies differing in local pitches only.

Adolescent↗
PubMed1987

Spatial constraints on attention to speech in the blind.

When sighted persons try to identify one of two speech utterances coming from different directions, they display both a frontal position advantage, i.e., better recognition of inputs from the front than of those from the rear, and a right-side advantage, better recognition of inputs from the right than of those from the left. The present study demonstrates a dissociation of the two effects in blind subjects (N = 10) who showed no frontal position advantage together with a right-side advantage superior to that of control sighted subjects (N = 16). There was no systematic difference between congenitally blind subjects and noncongenitals. The absence of frontal position advantage in the blind is consistent with the notion that this effect originates in the habit of sighted listeners to orient toward the source of heard speech. The occurrence of at least normal right-side advantage in the blind does not support recent suggestions of reduced lateralization of language functions in such subjects.

Adolescent↗
PubMed1987

Shifting ear differences in melody recognition through strategy inducement.

In a previous study, the pattern of ear superiority displayed by nonmusicians in a task where dichotically presented target melodies have to be recognized among four probes was found to be correlated with subjects' descriptions of their operating modes: those who reported focusing on critical local differences in pitch tended to show right ear advantage (REA) and the others LEA. The purpose of the present study was to examine if laterality patterns can be affected by treatments designed to induce particular strategies. Treatments supposed to orient toward analytic processing, advising attention to critical notes, with (Experiment 2) or without (Experiment 1) the additional task of reporting their location, produced the expected shift toward REA. To the contrary, treatments supposed to orient toward holistic processing, advising attention to overall contour or requesting aesthetic judgments (Experiment 1), failed to produce the expected shift toward LEA. The result can be attributed either to a basic difference in susceptibility to strategic control between the different operating modes or, more simply, to ineffectiveness of the present holistically oriented treatments.

Adolescent↗
PubMed1987

Finding parts within figures: a developmental study.

Preschool children, primary school children, and unschooled adults were tested on the part-probe task designed by Palmer. Relatively high scores were obtained with all groups on parts which had a 'good' relationship with the figure. However, the ability to find more deeply embedded segments was not present in the preschool children or in the unschooled adults. This indicates that the processes of postperceptual analysis necessary to find a part in a figure are neither built-in nor the consequence of mere cognitive growth, but depend on the instruction or experience usually provided in school. Such processes should not be confused with those that lead to form perception. Inspection of the part-figure pairs and of the corresponding detection scores suggests the importance of several stimulus properties.

Adult↗
PubMed1986

Speech-mediated retention in dyslexics.

Dyslexics (6 to 9 yr. old) and a control group of 12 normal readers (second-graders) were tested on a memory task with rhyming and non-rhyming items. The most important finding is that both groups were penalized by rhyme, indicating speech coding. It was observed that the dyslexics were not less penalized by rhyme than were controls. The present results are compared with those of other recent studies.

Child↗
PubMed1986

Evidence for early extraction of emergent properties in visual perception: a replication.

In conditions precluding focused attention, illusory conjunctions of triangles were more frequent when the emergent characteristic of closure was present in the display together with the component parts than when it was not. This replicates Treisman and Paterson's 1984 result, which is the strongest evidence available in favor of the notion of an early extraction of emergent properties.

Adult↗
PubMed1985

Ear differences in children at two years of age.

Twenty-six children (13 boys and 13 girls) aged from 21 to 35.5 months were presented with a dichotic test of recognition of familiar words. There was no significant ear difference on average, however, a clear right-ear preference did emerge in children of right-handed parents. This contrasted with the tendency toward a left-ear preference that was exhibited by children with at least one left-handed parent.

Child, Preschool↗
PubMed1985

Factors of hemifield differences in form discrimination.

The influence of some process-limiting variables on hemifield differences for nonsense shapes in a "same-different" classification task was examined. "Different" responses, but not "same," did show systematic effects. Weakly discriminable and unfamiliar shapes which were presented successively yielded a significant left-hemifield advantage, while highly discriminable and more familiar shapes presented simultaneously yielded a nonsignificant right-hemifield advantage. Discriminability, considered independently of the other variables, had effects in opposite directions: low discriminability tended to favor more the right than the left hemifield in each experiment, but the right hemifield more than the left when the comparison was made between experiments. The results are discussed in terms of the spatial-frequency model (Sergent, 1982b, 1983) and the analytic-holistic distinction.

Adult↗
PubMed1983

A Ponzo-like illusion left and right of fixation: a failed prediction.

Ponzo-like figures, with two parallel horizontal test lines superimposed on a pattern of converging background lines suggesting either a floor or a ceiling were presented in a tachistoscope unpredictably left or right of fixation, and the subjects had to compare the test lines as to length. The classical relative overestimation of the line closest to the apex of the background lines was obtained, but it was not stronger in the left visual field, as seemed to be predicted by at least two current generalizations concerning right hemisphere capacities: (a) that the right hemisphere is better at extracting spatial relations; (b) that its processing mode is more "holistic" and less "analytic" than that of the left hemisphere.

Distance Perception↗
PubMed1983

Task determinants of ear differences in melody processing.

In Experiment 1 nonmusicians were presented with dichotic melodies, which differed either on all pitches or by a single note, followed by a set of four binaural melodies. They were asked to recognize among the alternatives only one member of the dichotic pair in the "single-focus" task, and both dichotic melodies in the "double-focus" task. These different attention requirements led to a LEA in the first task which contrasted with the REA observed in the other task when melodies differed by all pitches. A possible confounding (fusion of the common pitches) prevents comparison of the tasks for melodies differing by a single pitch. The role of the extent of melody differences was further investigated in a second experiment by changing melodies on one, two, or three notes. No effect of material was observed on ear asymmetries. Task demands appeared as the most critical determinant of ear differences and are discussed in terms of their particular influence on the adoption of an analytic or holistic processing mode. Male subjects were found to be more responsive than females to analytic processing suggestions.

Adult↗