A technique for controlling speech disfluencies induced by delayed auditory feedback

On the basis of cybernetic models of speech it was hypothesized that “stuttering” induced by delayed auditory feedback could be significantly reduced if the Ss were provided with an alternate input to which they could attend. The results of the experiment supported the hypothesis. The possible implications for the treatment stuttering are discussed.     

Perception of nonlinguistic auditory rhythms by the speech hemisphere

Two groups of right-handed young adults were tested on a series of handedness measures and on dichotic nonverbal rhythmic sequences. Cross-validated multiple regression analysis revealed that all of the cerebral-lateralization/manual-praxis measures were positively related to the degree of left-hemisphere perceptual asymmetry for nonverbal rhythms (Crawford peg, scissor, handwriting, Crawford screws, tracing, total R = .67). Seventeen of the 52 subjects manifested significant (p < .05) left-hemisphere laterality coefficients for the dichotic stimuli. More complex rhythms elicited greater left-hemisphere perceptual preference. The results are discussed in reference to the concept of cerebral lateralization.     

Adult-child discourse: Developmental interaction between information processing and linguistic knowledge

In the present study, the discourse interaction between adult and child was examined in terms of the content of their utterances, and the linguistic and contextual relations between their messages, in order to investigate how children use the information from adults' input sentences to form contingent responses. The analyses described were based on longitudinal data from four children from approximately 21 to 36 months of age. Categories of child discourse, their development and their interactions with aspects of prior adult utterances form the major results of the study. Child utterances were identified as adjacent (immediately preceded by an adult utterance), or as nonadjacent (not immediately preceded by an adult utterance). Adjacent utterances were either contingent (shared the same topic and added new information relative to the topic of the prior utterance), imitative (shared the same topic but did not add new information), or noncontingent (did not share the same topic). From the beginning, the adjacent speech was greater than nonadjacent speech. Contingent speech increased over time; in particular, linguistically contingent speech (speech that expanded the verb relation of the prior adult utterance with added or replaced constituents within a clause) showed the greatest developmental increase. Linguistically contingent speech occurred more often after questions than nonquestions. The results are discussed in terms of how the differential requirements for processing information in antecedent messages is related to language learning.     

Infants' discrimination of internal and external pattern elements

Human infants' discrimination of changes in internal and external elements of compound visual patterns was investigated in four experiments employing a familiarization-novelty paradigm in which visual reinforcing patterns were presented contingent upon rate of high-amplitude nonnutritive sucking. In Experiment 1, 4-month infants discriminated changes in the shape of internal, external and both internal and external figures. One-month infants discriminated external changes in both internal and external figures, but failed to show reliable response recovery when only internal figures were changed. Experiments 2 and 3 failed to explain the 1-month results on the basis of poor resolution of internal figures by showing comparable discrimination of small and large singly-presented figures and by failing to find improved internal discrimination with large separation between internal and external figures. In Experiment 4, 1-month infants showed response recovery to figure additions made adjacent to the initial figure, but not to internal additions. The results are interpreted in terms of attentiveness by young infants to external pattern elements and may indicate early processing of figure-ground information. The developmental differences observed suggest an increased breadth of attention to pattern elements.     

A probe trial procedure for the study of children's discrimination learning and transfer

A discrimination reversal problem was presented to 192 children varying in age from 3 to 5 years. At the end of both the initial learning and transfer trials, probe trials were introduced to ascertain the response rule describing children's choices. Results were analyzed in terms of a binary division of the children according to their responses to the probe stimuli; children who responded errorlessly (concept responders) were contrasted with children who made errors on the probes (instance responders). Using this criterion, it was found that many children transferred in a way different from the way they learned the initial problem. There was no difference in the proportion of younger and older children responding conceptually to the original problem, but older children were more likely to transfer conceptually when standard geometric blocks were used as stimuli. Future studies must consider the possiblity that learning and transfer may be accomplished by different processes whose application differs with age, the nature of the stimuli, and the stage of training.     

Component processes of an overt rehearsal strategy in young children

The locus of facilitation due to rehearsal was investigated in three experiments with first-grade children. Several different overt acquisition strategies in a four-item sequential memory task were compared, including ordered repetition, item repetition, item labeling, and free strategy conditions. Experiment 1 showed that ordered repetition yields most of the facilitation due to rehearsal, and Experiment 2 demonstrated that the facilitation cannot be attributed to spaced practice. Experiment 3 showed that retrieval practice during study may improve memory performance but that the facilitation due to ordered repetition and retrieval practice is relatively short term. Mere repetition and labeling were not found to be significant component processes of rehearsal in any of the experiments. These results were discussed in terms of their relevance to rehearsal training studies and a differentiation between maintenance and elaborative rehearsal.     

On the representation of language in the right hemisphere of right-handed people.

Laterality experiments using reaction time were conducted to assess the performance of the right hemisphere of normal people on verbal tasks. The results show that if the task calls for pictorial encoding of visually presented verbal material, then the right hemisphere's performance is superior to that of the left. When the task calls for linguistic analysis, the minor hemisphere displays no aptitude in dealing with the task. The latter finding is at variance with data from split-brain research. To reconcile these differences, it was proposed that language functions, though represented in the right hemisphere of normal people, are functionally localized in the left. When the control which the left hemisphere exerts over the right is weakened or removed, e.g., by commissurotomy, right hemisphere language is released. The application of this model to other neurological phenomena is briefly discussed.     

Language acquisition following hemidecortication: Linguistic superiority of the left over the right hemisphere

The language development of three 9- and 10-year-old children possessing only a right or a left hemisphere was studied. Surgical removal of one brain half antedated the beginning of speech, so each child has acquired speech and language with only one hemisphere. Different configurations of language skill have developed in the two isolated hemispheres: phonemic and semantic abilities are similarly developed but syntactic competence has been asymmetrically acquired. In relation to the left, the right brain half is deficient in understanding auditory language, especially when meaning is conveyed by syntactic diversity; detecting and correcting errors of surface syntactic structure; repeating stylistically permuted sentences; producing tag questions which match the grammatical features of a heard statement; determining sentence implication; integrating semantic and syntactic information to replace missing pronouns; and performing judgments of word interrelationships in sentences. Language development in an isolated right hemisphere, even under seizure-free conditions, results in incomplete language acquisition.