The dilution effect: Nondiagnostic information weakens the implications of diagnostic information

In a series of studies, subjects were asked to make predictions about target individuals. Some subjects were given information about the target which pretest subjects had judged to be “diagnostic”—that is, had judged to be usefully predictive of the outcome. Other subjects were given a mix of information judged to be diagnostic and information judged to be “nondiagnostic” by pretest subjects—that is, judged to be of little value for predicting the outcome. Subjects given mixed information made much less extreme predictions than did subjects given only diagnostic information. It was argued that this “dilution effect” occurs because people make predictions by making simple similarity judgments. That is, they compare the information they have about the target with their conception of outcome categories. The presence of individuating but nondiagnostic information about the target reduces the similarity between the target and those outcomes that are suggested by the diagnostic information. One of the major implications is that stereotypes and other “social knowledge structures” may be applied primarily to abstract, undifferentiated individuals and groups and may be largely set aside when judgments are made about concrete, individuated people.     

Performance of dyslexic children on speech perception tests

Several researchers who have compared the performance of dyslexic and normal-reading children on a variety of different tasks have suggested that dyslexic children may have subtle deficits in the phonemic analysis of spoken as well as written language. Thus it is of interest to know how children who have extraordinary difficulty learning to read can perform explicity auditory-phonetic tasks. Seventeen dyslexic children (10 years of age) and a group of 17 controls were administered tests of identification and discrimination of synthesized voiced stop consonants differing in place of articulation. These were tests of the type used to study categorical perception in adults, adapted for use with young children. Significant differences between dyslexics and controls were found in both kinds of tasks; the pattern of identification and discrimination differences suggests an inconsistency in the dyslexics' phonetic classification of auditory cues. A significant relationship was found between reading level and speech discrimination.     

The psychometric attributes of Furth's nonverbal conservation test

The study examined the suitability of Furth's nonverbal conservation test as a psychometric tool for measuring individual differences in Zambia. The subjects included normal and mentally deficient Zambian children aged 7–13 years. The test was validated against age differentiation, differentiation of different intellectual levels, and school performance. The results showed that scores on the test increased significantly with increase in age, correlated positively and significantly with school scores, and differentiated normal from mentally deficient children. Within the normal sample the test also differentiated dull from average children; within the deficient sample the test did not differentiate the moderately mentally deficient from the severely mentally deficient. These results are explained by reference to the characteristics of the test, performance on which requires learning, memory, and perceptual abilities.     

Selective involvement of the auditory-verbal modality in an acquired communication disorder: Benefit from sign language therapy

A 39-year-old female suffered bitemporal infarctions and exhibited an unusual behavioral syndrome of muteness and impaired auditory comprehension, with milder aphasic deficits in reading and writing. The anatomic basis of this modality-selective communication disorder appeared to involve both peripheral perceptual and motor as well as “central” language mechanisms. The patient's ability to communicate was greatly aided by instruction in Amerind and Ameslan Sign Language, in which she learned more than 100 signs. Patients whose acquired language deficits spare modalities of input or output may be ideal candidates for sign language therapy.     

Retention of verbal information by rehearsal in relation to the fluency of verbal output in aphasia

The purpose of the present study was to determine if aphasic subject groups differentiated by the fluency of their verbal output employed rehearsal as a strategy for maintaining verbally coded information in primary memory. A task based upon the Brown-Peterson paradigm was administered to 10 fluent aphasic patients, 10 nonfluent aphasic patients, 10 right-brain-damaged patients, and 10 nonneurological patients. The findings indicate that the nonfluent aphasic patients did not rehearse the verbal information while the fluent aphasic, right-brain-damaged, and nonneurological patients did rehearse. In addition, both fluent and nonfluent aphasic patients encoded significantly less information into the memory system initially and performed worse on the task overall than right-brain-damaged and nonneurological patients.