Central auditory processing. V. Ear advantages for acoustic stimuli in baboons

Four baboons (Papio cynocephalus) were tested using food as reward for ear advantages in the monaural discrimination of pure tones, three-tone musical chords, synthetically constructed consonant-vowels, and vowels. All four animals showed highly significant and reproducible ear advantages for each class of acoustic stimulus with marked individual differences in the direction of their ear asymmetry. The results obtained in these experiments represent the first evidence of ear asymmetries for different classes of acoustic stimuli in a nonhuman species. Further, the ear advantages found in these animals under monaural conditions resemble those obtained with dichotic presentation in human subjects and thus suggest that the baboon may be a valuable model of central auditory processing of various types of acoustic stimuli in man.     

Contrasting cases of Italian agrammatic aphasia without comprehension disorder

This study examined the effects of different concurrent verbal memory loads on a recognition accuracy task using bilaterally presented nouns. Four different memory load conditions were examined. They varied along a size dimension of either three or six words and along a complexity dimension of either easy concrete nouns or difficult highly abstract nouns. In each of the above conditions and in one control group, order or word report was controlled and in a second control group subjects were free to report the lateralized words in any order they wished. There were 20 subjects in each of the six groups. As expected, a significant right visual field superiority for verbal processing was obtained. there were no main effects of size of memory load nor complexity of m emory load on the laterality patterns. More subtle fluctuations in the patterns were found in the form of significant interactions between memory load, order of word report, and visual field. These interaction effects suggest that words reported second in the bilateral task, are more susceptible to the interfering effects of either larger or more complex memory loads. This is particularly true for right visual field words. While these data generally support a structural model of hemispheric organization, the interaction effects suggest that modifications must be made to the basic model to account for such factors as hemispheric capacity limits and order of report in the bilateral task.     

Inferential processing of context: Studies of cognitively impaired subjects

Language comprehension tasks involving pronoun coreference were administered to a group of demented patients, a group of patients with cardiac disease, and groups of normal elderly persons and young adults. Pronoun coreference was constrained by either lexical, syntactic, or contextual cues. No differences were found between old and young subjects for any task. While the demented patients were impaired on all tasks, the cardiac patients were specifically impaired in the inferential processing of context.     

Aphasia following a right thalamic hemorrhage

A left-handed patient with a right thalamic hemorrhage and disordered speech is described. Sequential examinations and aphasia testing were done during a 1-year follow-up period and the results are reported. This case supports those authors who have described characteristics they feel are helpful in diagnosing disordered speech associated with thalamic lesions. Paucity of speech, reduced voice volume, anomia, some paraphasia, and severe dysgraphia were present, but comprehension and repetition were relatively preserved. She showed modest improvement with time. This case also confirms that thalamic involvement in speech is a dominant, rather than a specifically left hemispheric function.     

An awareness approach to the covert symptoms of stuttering

Speech-language clinicians working with the confirmed stuttering client are often faced with the clinical management of the covert symptoms of stuttering in addition to the more observable and measurable overt symptoms. The authors report the successful use of awareness techniques to exaggerate the subjective experience of these covert symptoms and encourage the use of these techniques as an adjunct to the counseling and desensitization procedures traditionally employed. A transcribed clinical management session in which several awareness techniques are used to aid the client in an introspective examination of “anticipation of stuttering,” is analyzed in order to reach some specific recommendations for using awareness techniques in the clinical management of the covert symptoms of stuttering.     

Further study of the electrophysiological correlates of lexical decision

Discriminations were required between words, pseudohomophones, and visually matched nonwords. Two tasks were employed, one which could be accomplished on the basis of a visual code (the REAL task, involving discrimination between words and both types of nonword) and another necessitating the use of a phonological code (the REAL/PSEUD task, words and pseudohomophones vs. nonwords). ERPs were recorded from three midline sites and from left and right inferior parietal sites. Two principal results were observed, (i) the peak latency of a late positive component, P637, covaried with RT, with variations in latency of around one half the corresponding RT variations, and (ii) the peak-to-peak amplitude of N100-P187 interacted with stimulus and task, such that it was larger for nonwords in the REAL task and words in the REAL/PSEUD task. No taskor stimulus-dependent asymmetries were observed in any ERP component. The P637 latency data support a model of RT variation based on the interaction of changes in parallel response preparation and stimulus evaluation processes. The observations with respect to N100-P187 suggest that ERPs are sensitive to factors related to the early processing of words and word-like visual material.     

The ecological approach to perceiving as a foundation for understanding the development of knowing in infancy

The ecological thesis of direct realism is used as a framework for examining the development of knowing in human infancy. When information for perceiving is defined ecologically (i.e., relative to the situational context and to the physical dimensions, capabilities, and needs of the perceiver), knowing need not be construed as the act of using representations to give meaning to acts or percepts. Knowing, alternatively, is the act of noticing affordances, situation and perceiverspecific meanings of objects, according to their value to the perceiver for achieving specific goals. Changes with development in infant sensorimotor functioning may, in this view, be explained by a process of increasing economy in noticing potentially available affordances, rather than a process of constructing a representational system for making present something not present. Studies of three infant skills widely attributed to the onset of representation are examined with regard to this ecological thesis. Results indicate that the noticing of affordances is critically involved in each of these skills.     

Conflict,learning, and Piaget: Comments on Zimmerman and Blom's “Toward an empirical test of the role of cognitive conflict in learning”

A brief historical account dealing with the concept of psychic conflict is first presented, followed by an examination of Piaget's equilibrium/equilibration model and the relevance of the concept of conflict to that model. A critical analysis of B. J. Zimmerman and D. E. Blom (Developmental Review, 1983, 3, 18–38) is then presented, after which suggestions are made regarding future directions research efforts pertaining to Piaget's conflict/learning formulation might fruitfully take.     

Sociolinguistic contexts of the preschool

Two studies were conducted to determined the effects of specific learning centers on preschoolers' functional uses of language. In Study 1, preschoolers in three separate same-age classrooms (2-, 3-, and 5-year-olds) were observed on a time sampling scheduling during their free play periods for four weeks. Preschoolers' individual utterances were coded as serving one or more than one function; functions were defined following Halliday. The housekeeping and block centers tended to elicit the most individual and multifunctional utterances. The fantasy play and social interaction among children in these centers were thought to be responsible for this mature use of language.In Study 2, same-age and same-sex dyads from two age groups (4- and 5-year-olds) were observed in experimental settings playing with blocks alone and with dramatic props alone. Both contexts elicited a predominance of imaginative language, though the dramatic context elicited more imaginative language than the blocks. With age, children generated more individual functions and multifunctional utterances.