Auditory Evoked Potential Variability in Schizophrenia. II. The Application of Discriminant Analysis

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Average evoked potentials, Schizophrenic patients

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The data recorded by Callaway et al. in a study of degree of dissimilarity of two-tone average evoked potentials (AEPs) in normal and schizophrenic patients were analyzed by the Step-Wise Discriminant Analysis (SWDA) technique. The analysis was undertaken to determine if (a) groups of single-trial records obtained with two dissimilar tones show a greater dispersion than groups of single-trial records obtained with identical tones, and (b) the degree to which the dissimilarity of two-tone AEPs, if found, is consistent between subjects (i.e., the same evoked potential components contribute to the dissimilarity in an equivalent manner).

The application of this analysis to the two-tone AEPs demonstrates that although there is indeed a somewhat increased dissimilarity between the AEPs to dissimilar tones, there is no appreciable difference in this respect between schizophrenic and normal subjects. Furthermore, there is little consistency in the AEP components that differentiate the two AEPs from one subject to the next.

The results of this analysis in conjunction with those reported in a companion paper by Callaway et al. (1970) suggest that the previously reported differences between normal and schizophrenic subjects are largely the result of the increased variability in the AEP of schizophrenics rather than of a consistent tendency of the patients to concentrate on trivial differences between the tones.

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Electroencephalography and Clinical Neurophysiology, v. 29, issue 5, p. 429-440.