Classes and collections: Conceptual organization and numerical abilities

Collections (e.g., forest, army) and classes (e.g., trees, soldiers) are natural concepts that differ in their organizational principles. Collections are organized into part-whole relations (e.g., trees are parts of a forest). Classes are organized according to class inclusion relations (e.g., oaks are kinds of trees). Because of their part-whole organization, collections are assumed to have greater psychological coherence than classes and therefore an advantage on tasks that require thinking about an aggregate as well as the individuals in it. Number requires aggregate analysis since it is a characteristic of sets, not of individuals. Four studies tested the hypothesized collection advantage in numerical reasoning tasks. In each, children viewed identical displays that were labeled with either class or collection terms. With perceptual input constant, the collection labels in contrast to the class labels promoted children's insight into certain numerical principles and facilitated the use of these principles in a variety of numerical tasks. Collection labels appear to induce a cognitive reorganization of importance to the child: the shift from inclusion to part-whole relations.     

The effects of differential reinforcement on generalized imitation

The present study examines the transfer of imitative learning to other nonimitative performance conditions and compares imitative and nonimitative performance under contingencies of differential reinforcement for S⁰ behavior, differential reinforcement for nonimitative behavior, and extinction. Many authors have suggested that a child's continued imitative performance of rewarded S^D and unrewarded S^Δ behavior is a function of subtle social cues or experimental demand present in most generalized imitation procedures. The two experiments presented here support that conclusion but also provide evidence that conclusions drawn from such generalized imitation studies were generally accurate. Even though a child's trial-by-trial imitative performance appeared to be a function of procedural artifacts, the child's later performance in the role of a model indicated that a functionally interdependent generalized response class of imitative behavior had been learned while the child imitated. As such, these experiments generally supported Baer's secondary reinforcement hypothesis for imitative performance and suggest that future research employ nonimitative tasks such as reversed imitation as a measure of imitative learning.     

Cerebral asymmetry for American Sign Language: The effects of moving stimuli

Previous studies of cerebral asymmetry for the perception of American Sign Language (ASL) have used only static representations of signs; in this study we present moving signs. Congenitally deaf, native ASL signers identified moving signs, static representations of signs, and English words. The stimuli were presented rapidly by motion picture to each visual hemifield. Normally hearing English speakers also identified the English words. Consistent with previous findings, both the deaf and the hearing subjects showed a left-hemisphere advantage to the English words; likewise, the deaf subjects showed a right hemisphere advantage to the statically presented signs. With the moving signs, the deaf showed no lateral asymmetry. The shift from right dominance to a more balanced hemispheric involvement with the change from static to moving signs is consistent with Kimura's position that the left hemisphere predominates in the analysis of skilled motor sequencing (Kimura 1976). The results also indicate that ASL may be more bilaterally represented than is English and that the spatial component of language stimuli can greatly influence lateral asymmetries.     

The voice problems of stutterers: A practical approach from clinical experience

Voice disorders, which may be caused by the stuttering problem, have been noted in at least one-third of stutterers seen. Basically, stutterers have false speech images that normal speech is perfect and without natural dysfluencies (repetitions, pauses, etc.). Many stutterers also have erroneous vocal images of how they should or should not sound. Both images control speech and voice. Clinical experience indicates that vocal rehabilitation should be used in conjunction with speech therapy for many stutterers.     

Remembering information related to one's self

How does memory for an incident vary depending on whether, and how, the person relates the information to himself? Trait adjectives are better remembered if they were judged in reference to oneself rather than judged for meaning or sound. Our first experiment found a similar mnemonic advantage of referring a described episode or object to some event from one's life. Pleasant events were remembered better than unpleasant ones. A second experiment found incidental memory for trait adjectives was equally enhanced by judging each directly in reference to one's self-concept or indirectly by retrieving an episode either from one's life or from one's mother's life. Contrariwise, memory was poorer when traits were judged in reference to a less familiar person. Thus, good memory depends on relating the inputs to a well-differentiated memory structure.     

The effects of distance between interactants and subject anxiety on conjugate lateral eye movements

Ehrlichman and Weinberger (1978, Psychological Bulletin 85, 1080-1101) have suggested that the distance between participants during face-to-face interviewing may be a significant determinant of directional patterns of conjugate lateral eye movements (CLEMS). As predicted, at the longer, social distance CLEMS were dependent on the verbal or spatial nature of questions; when interactants were at a closer, personal distance CLEMS became more consistent in direction, regardless of problem type. Distance manipulation also differentially altered CLEM patterns for the two sexes.     

Hemispheric asymmetry,early visual processes,and serial memory comparison

Observers indicated whether a single probe letter presented to the left visual field/right hemisphere (LVF-RH) or to the right visual field/left hemisphere (RVF-LH) matched one of two, three, four, or five set letters in both name and case. For positive trials during the initial experimental session, the slope of the linear memory set size reaction time function was increased by perceptually degrading the probe letter on LVF-RH trials, but not on RVF-LH trials. In addition, perceptual degradation of the probe letter increased the intercept of the memory set size function more on RVF-LH trials than on LVF-RH trials. During subsequent experimental sessions, the same pattern of intercept results was obtained but perceptual degradation of the probe no longer changed the slope for either LVF-RH or RVF-LH trials. However, the slopes were uniformly lower on RVF-LH trials than on LVF-RH trials. The major results are consistent with hypothesized right-hemisphere efficiency for early processing stages and left-hemisphere efficiency for serial processing of alphanumeric information. The results further illustrate the importance of separating stages of processing in studies of cerebral laterality and indicate that the relative difficulty of the various stages can be a determinant of laterality results.     

Simulating a skilled typist: a study of skilled cognitive-motor performance

We review the major phenomena of skilled typing and propose a model for the control of the hands and fingers during typing. The model is based upon an Activation-Trigger-Schema system in which a hierarchical structure of schemata directs the selection of the letters to be typed and, then, controls the hand and finger movements by a cooperative, relaxation algorithm. The interactions of the patterns of activation and inhibition among the schemata determine the temporal ordering for launching the keystrokes. To account for the phenomena of doubling errors, the model has only “type” schemata—no “token” schemata—with only a weak binding between the special schema that signals a doubling, and its argument. The model exists as a working computer simulation and produces an output display of the hands and fingers moving over the keyboard. It reproduces some of the major phenomena of typing, including the interkeystroke interval times, the pattern of transposition errors found in skilled typists, and doubling errors. Although the model is clearly inadequate or wrong in some of its features and assumptions, it serves as a useful first approximation for the understanding of skilled typing.     

Impairment of voice and face recognition in patients with hemispheric damage

Voice and face recognition were tested in 21 left- and 9 right-hemisphere-damaged patients. Test materials were photographs and recordings of famous political and entertainment personalities. Pathological face recognition (prosopagnosia) and voice recognition (phonagnosia) were both significantly more prevalent in the right-hemisphere group. Only one instance of prosopagnosia and one of phonagnosia were observed in the left-hemisphere group, all of whom were aphasic. Of the right-hemisphere cases, there were four instances of each agnosia, with three patients showing a dual impairment. These findings are discussed in relation to differential modes of processing by the two cerebral hemispheres.