Clustering of disfluency in nonstuttering childrens' early utterances

The clustering of disfluency within early utterances in the speech of four nonstuttering children was examined. During the developmental period their mean length of utterance was between 2.25 and 3.0 morphemes. The frequency and characteristics of the clustered disfluencies are described and compared with single disfluent moments. Clusters of two disfluencies were analyzed for interactive effects of positional preference and type. Results were similar to those found in older preschool nonstuttering speakers, demonstrating the normal developmental nature of clustering in early sentences. Implications for using this temporal measure to differentially diagnose normal from abnormal disfluency are discussed.     

Possible effects of forced report order on tachistoscopic recognition of bilaterally presented stimuli: A response to Young and Ellis

Comparing visual field asymmetries for bilaterally presented words and corresponding line drawings, we found an RVF advantage for words and no visual field asymmetry for line drawings. We suggested that the RVF advantage previously obtained by Young, Bion, and Ellis (Brain and Language, 11, 54–65, 1980) for bilaterally presented line drawings may have resulted from a forced order of report procedure, noting that the RVF advantage was greater on trials on which subjects were forced to report in the nonpreferred right-to-left order. Young and Ellis (Brain and Language, 20, 166–171, 1983) attempt to discredit this claim and maintain their hypothesis that the RVF advantage for line drawings is attributable to better temporary storage of these stimuli by the left than the right hemisphere. In the present article, we present in greater detail our arguments for the effects of forced order of report on the perception of bilaterally presented stimuli and refute Young and Ellis's ibid. criticisms of this proposal.     

Methinks they do protest too much

A serious methodological error was committed by Stephens et al. (1972), the protestations of the present critics notwithstanding. When studying the relationship between two sets of variables, it is clearly wrong to hold chonological age constant in one set and allow it to vary in the other. This error spuriously reduces the correlation between the two sets. A demonstration that the two sets define different first-order factors provides very little information about the degree of relationship present, which must be derived from the intercorrelations of those factors. In the original research, these were also biased by the methodological error. The conclusion of Humphreys and Parsons that Piagetian tasks and intelligence tests could be used interchangeably is reinforced. The hypothesis that the relatively small amount of unique variance in the Piagetian composite is relatively unimportant psychologically can only be discarded on the basis of good empirical research, not debater's arguments.     

Statistical significance tests for binormal ROC curves

Statistical significance tests are derived and evaluated for measuring apparent differences between an obtained and an expected binormal ROC curve, between two independent binormal ROC curves, and among groups of independent binormal ROC curves. A binormal ROC curve is described by two parameters which represent the spread of the means and the ratio of the standard deviations of the two underlying Gaussian decision variable distributions. To test the significance of apparent differences between or among ROC curves, approximate χ² statistics for each of the three tests were constructed from maximum likelihood estimates of the two parameters defining the binormal ROC curve. The performance of each test statistic was evaluated by simulating five-category rating scale data with equal numbers of noise and signal-plus-noise trials (set at 50, 250, and 500) for each of three typical ROC curves. For the significance test involving only one ROC curve, rating scale data were generated from the chance diagonal of the ROC space also. Although test performance was found to be somewhat dependent on the number of trials and on the location of the ROC curve in the ROC space, comparisons of the obtained and expected fractions of (falsely) significant results at various α levels showed the proposed statistical significance tests to be reliable under practical experimental conditions.     

The morphological asymmetry of the hemispheres and cerebral dominance for speech: A possible relationship

The asymmetry of the posterior Sylvian branches of the middle cerebral artery was examined on the carotid angiograms of 59 patients in whom the lateralization of speech representation was known from sodium amobarbital (Amytal) studies. The usual asymmetry of these vessels was found to be present in the group of patients with left-hemisphere speech representation but significantly reduced in patients with atypical cerebral dominance for speech. A model of the inheritance of handedness and cerebral dominance is extended to take account of these results.     

Developmental auditory agnosia in the severely retarded: A further investigation

The hypotheses were investigated that (a) ability to recognize the auditory perceptual stimuli for familiar events is a developmental correlate to language acquisition and (b) the low functioning mentally handicapped suffer from auditory agnosia and are impaired in this ability. The subjects were 42 nonretarded children of ages 3 through 6 and 53 severely and moderately retarded, noninstitutionalized students. The retarded subjects were matched by mental age to the chronological age of the nonretarded children. The stimuli were 49 environmental sounds; the task consisted of sound-and-picture matching-to-sample. Group membership and developmental age were the factors in an analysis of variance design. The results revealed a strong effect of developmental age (p <. 0001). The effect of group was not significant, indicating that auditory agnosia may not be common among the lower functioning retarded. The assumption that agnosia may be a major factor underlying the language disability of the severely retarded was reexamined. It was suggested that the severely retarded achieve the requisite perceptual-semantic knowledge base for language too late, after the critical age for spontaneous and efficient language learning has passed.     

Verbal and nonverbal recognition memory in aphasic and nonaphasic stroke patients

The ability to retain lists of verbal and nonverbalizable items across recurrent recognition tasks was tested in three groups: (1) stroke patients with a left-brain lesion and aphasia, (2) stroke patients with a right-brain lesion and left hemiplegia, and (3) nonneurologically impaired outpatients. As determined with signal detection measures, aphasics were deficient in discriminating words that were to be remembered from those that were not; their recognition of nonverbal visual (geometric art) or auditory (bird calls) patterns, however, was unimpaired. Left hemiplegics showed the opposite pattern. After a long-term interval (<10 min), correct recognition of words was diminished in all groups whereas recognition of visual patterns increased. Both groups of stroke patients adopted material-specific decision criteria which in part accounted for the dissociation of verbal and nonverbal recognition memory by laterality of lesion. Item analysis indicated that aphasics' verbal memory difficulties were affected by acoustic-semantic confusion of list words.     

Sensitivity of 5- and 7-month-old infants to pictorial depth information

An Ames (1951, Psychological Monographs, 65(1, Whole No. 324)) static trapezoidal window, under monocular view, was used to test young infants' responsiveness to pictorial depth. When adults view this display monocularly with the smaller side of the window rotated toward them, they report that the orientation of the display becomes ambiguous: When the head is moved, the window may appear to be in the fronto-parallel plane or either side may appear closer. The 7-month-olds we tested appeared to experience a similar ambiguity; they reached to the near side of the rotated trapezoidal window with significantly less consistency or directedness than infants in a control group tested with a rotated object that lacked pictorial depth information. When 5-month-olds were tested, however, they reached with equal consistency to the closer side of the trapezoidal window and of the control display, apparently uninfluenced by the pictorial depth information available in the trapezoidal window. Thus, sensitivity to the pictorial information for depth that is present in the trapezoidal window appears to develop after the age of 22 weeks.