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Biomedical subjects

I Nachson

Publications and source records attributed to I Nachson.

5 recordsLinked to original sources
PubMed1999

Impairments in judgment of chimeric faces by schizophrenic and affective patients.

The hypothesis that schizophrenic and affective patients have differential impairments in judgment of facial emotional expressions was tested on 55 right-handed patients: 15 in each of two groups of schizophrenic patients, with positive and negative symptoms; and 10 in each of two groups of bipolar affective patients, in manic and depressive states. In addition, 37 normal control subjects were also tested. The subjects were presented with eight schematic drawings of chimeric faces (each depicting a positive emotion in a given hemiface, and a negative emotion in the other hemiface), as well as with two drawings of composite faces (each depicting either a positive or a negative emotion). Subjects judged the emotions depicted by the facial expressions, as well as their intensity. The data, analyzed by analyses of variance, showed that normals judged the chimeric expressions on the basis of the emotions depicted by the left hemifaces. This tendency was weaker among the psychiatric patients. Schizophrenics with negative symptoms judged positive expressions in the left hemifaces as depicting negative emotions, and negative expressions as depicting positive emotions. Schizophrenics with positive symptoms and manic patients judged all expressions as depicting positive emotions. Depressive patients showed a stronger tendency to judge negative expressions as depicting negative emotions than positive expressions as depicting positive emotions. No significant group differences appeared in judgment of composite faces (except for schizophrenic with negative symptoms who were more accurate in judging positive than negative expressions). Patients performances were interpreted in terms of differential dysfunctions in posterior areas of the right cerebral hemisphere which might be associated with bilateral effects of dysfunctions in anterior cerebral areas.

Adult↗
PubMed1997

Dichotic listening to temporal tonal stimuli by good and poor readers.

The hypothesis that reading disability is associated with impairment in the lateralization of temporal stimuli was tested by presenting 123 good- and poor-reading boys (Grades 4 through 6) with dichotic sets of temporal and nontemporal tonal stimuli for recognition. Reading ability was assessed by measuring proficiency in reading consonants, vowels, words, sentences and short stories. On the tone test, good readers showed a right-ear advantage in reporting the temporal stimuli, and a left-ear advantage in reporting the nontemporal stimuli. Poor readers showed the reversed pattern of response. Since right-ear advantage in report of given stimuli indicates left-hemispheric dominance for processing those stimuli, the data seem to suggest a link between reading disability and left-hemispheric dysfunction in processing temporal stimuli.

Acoustic Stimulation↗
PubMed1995

The contribution of external and internal features to the matching of unfamiliar faces.

The relative efficacy of external and internal features in matching unfamiliar faces was studied in three experiments in which the subjects matched target and test faces differing in terms of external or internal features, or both. In Experiment 1 only full congruency between target and test faces was considered a match; in Experiments 2 and 3 faces sharing the same external and internal features were also considered to be matches. A total of 100 subjects matched 192 pairs of target and test faces in a "same-different" task. Reaction times and matching errors were recorded for analyses of variance. In all three experiments performance was best when either all features matched or all features mismatched, with mismatches having a slight edge. When matches of external and internal features with the target faces were inconsistent with each other, mismatches of external features led to faster responses in Experiments 1 and 2, and mismatches of internal features led to faster responses in Experiment 3. The results suggest that since faces are configurational stimuli, face matching is influenced by the non-relevant set of features; and that mismatches, especially of external features, influence face matching more than matches do.

Face↗
PubMed1995

On the modularity of face recognition: the riddle of domain specificity.

The present paper focuses on the modular attributes of face recognition, defined in terms of domain specificity. Domain specificity is examined by looking into the innate nature of face recognition, the special effects related to the recognition of inverted faces, the specificity of electrophysiological responsivity to facial stimuli, and the specific impairment in face recognition associated with localized brain damage. Converging evidence from these sources seems to consistently show that face recognition is not qualitatively unique, as it proceeds in a manner similar to the recognition of other visuospatial objects. However, it seems to be special in that it may involve specific mechanisms dedicated to face recognition. Among infants, differential responsivity to faces and to other objects in terms of age of onset, attraction and course of development, seems to indicate the operation of a special process. Unusual inversion effects in face recognition might be due to the special expertise that humans develop for recognizing upright faces. Face-selective single unit responses in the monkey's brain implies the existence in the visual system of cells which are exclusively dedicated to the processing of facial stimuli. Finally, in prosopagnosia localized brain damage is linked to a specific inability to recognize familiar faces. Taken together, the data seem to show that some elements in the process of face recognition are domain specific, and in that sense, modular.

Agnosia↗