A model of perceptual classification in children and adults

The developmental trend from overall-similarity to dimensional-identity classifications is explained by a quantitative model. I begin with the assumption that objects are represented in terms of constituent dimensions and that the representation of objects changes little with development. Given this assumption, the model has three major parts. First, the similarity between objects is a function of the combination of the constituent dimensional differences. I propose developmental change in the likelihood that dimensions are differentially weighted in the calculation of similarity. Second, the perceived similarities between objects are valued for the purpose of constructing classifications. I propose that similarities are valued more dichotomously with age, such that identity becomes increasingly special. Third, the valued similarities are used to choose the best classification of those possible. The model provides good qualitative fits to the extant data. Three experiments examining classifications in 2- to 8-year-olds and in adults support specific new claims of the model. The data and the model provide new insights about development, classification, and similarity.     

Contributions of a supportive work environment to parents' well-being and orientation to work

Examined the joint and unique contributions of informal social support in the workplace and formal, family-responsive benefits and policies provided by employers to the job-related attitudes and personal well-being of employed parents with a young child. Eighty married men, 169 married women, and 72 single women with a preschool child completed a survey concerning social support from co-workers and supervisor, utilization of family-responsive benefits and policies, readiness to leave the employer for additional benefits, job satisfaction, organizational commitment, role strain, and health symptoms. Among the findings: (a) Fathers and mothers expressed equal levels of job satisfaction and organizational commitment, but mothers reported more role strain and health symptoms; (b) nearly 48% of married women's organizational commitment was accounted for by measures of support in the workplace; (c) informal social support at work was significantly more important to men's well-being than that of women; and (d) formal, family-responsive policies appeared more consequential for the prediction of women's role strain, perhaps because of women's greater responsibility for adjusting work life to meet the demands of family roles.     

Altering memory through recall: The effects of cue-guided retrieval processing

Three experiments were designed to investigate the influence of initial recall on memory by assessing delayed recall after different immediate cued-recall tests. In all experiments, subjects performed semantic and phonemic encoding tasks on a word list. The subjects then received a cued-recall test that cued the target using the same word as the context word in the encoding task, a test that cued the target with a word from the same level at which the target was encoded, a test that cued the target with a cue from a different level at which the target was encoded, or no immediate-recall test. One day later, the subjects performed a final cued-recall test in which the type of cue (semantic or phonemic) was varied. Consistently, delayed recall was facilitated primarily when the cue on the immediate test was from the same level as the cue on the delayed test. This pattern of facilitation suggests that immediate cued-recall produces an elaboration of an existing memory representation that is closely tied to the type of cue used on the immediate test.     

Supportive and problematic social interactions: A social network analysis

Assessed the number of sources of supportive and problematic social interactions in the total social network as well as the number who were the sources of consistently supportive or problematic interactions in a sample of 2nd year medical students. Number of problematic interaction sources was hypothesized to be more predictive of psychological and physical well-being than number of supportive interaction sources. Results showed that total supportive and total problematic interaction sources were equally predictive of life satisfaction. The presence of at least one individual who is a consistent source of problematic interactions was most predictive of lower life satisfaction. Results indicate the importance of studying both supportive and problematic social interactions. They also suggest that interactions with individuals that are consistently problematic may negatively impact upon well-being.     

Evoked potentials and the study of sentence comprehension

Evoked brain potentials were used to monitor moment-by-moment decisions during language comprehension. Subjects read sentences containing temporary syntactic ambiguities for which one of the possible interpretations was semantically implausible. The N400 component of the evoked potential, which is sensitive to implausibility, was used to discover when during a sentence subjects made a decision about the ambiguity. The results demonstrate that readers try to interpret a syntactic ambiguity early in a sentence rather than waiting for disambiguating information. This introduces a new way to use brain activity to study sentence comprehension processes.     

A neuroscience model of stuttering

Using motor control systems analysis and a reductionist approach, we provide a unified model of stuttering. This model views stuttering as a momentary instability in a complex multiloop control system. The model predicts the temporal conditions under which this instability will occur. Furthermore, these temporal conditions account for the efficacy of fluency-evoking maneuvers, therapy, and the variability of speech output in stutterers.     

Behavioral correlates of developmental expressive language disorder

The association of behavior problems with preschool language disorders has been documented extensively. However, researchers have typically failed to differentiate subgroups of language-impaired children, to use observational data in documenting the behavior disorders, or to study children at the youngest ages. Using a multimodal assessment, this study examined parent-child interaction and behavior problems in a clearly defined subgroup of language-impaired children, those with developmental expressive language disorder (ELD). These children exhibit a delay in expressive language compared with receptive language and nonverbal cognitive skills. Subjects were identified and studied at the youngest age at which the disorder can be assessed. A group of ELD children, averaging 27 months of age, was contrasted with a group of normally developing children, matched for age, sex, and receptive language ability. Groups were compared on observed parent-child interactions as well as maternal responses on the Parenting Stress Index, the Eyberg Child Behavior Inventory, and a behavior-related structured interview. ELD children, when compared with normally developing children, exhibited higher levels of negative behavior and were perceived as different by their parents.Portions of these data were presented at the biennial meeting of the Society for Research in Child Development, Baltimore, April 1987, and at the annual meeting of the Society for Pediatrie Research, Anaheim, California, April 1987. This work has been supported by NIMH grant no. 1 R03 MH41603 to author Fischel, and by NICHD grant no. 1 ROI HD19245 to authors Whitehurst and Fischel. It has also been supported by grants of equipment from Commodore Business Machines, Inc., Koala Corporation, and NEC Telephones. We thank the Department of Pediatrics at the Nassau County Medical Center for the use of their facilities.     

Binocular depth from surfaces versus volumes

Subjects were asked to compare the relative depths of two binocular targets embedded in different random dot stereogram backgrounds. The disparities of the background points were either randomized, corresponding to a scattering of points within a volume, or arranged according to a sawtooth (triangle-wave) disparity profile (i.e., a set of slanted planar surfaces separated by sharp depth discontinuities). When the targets were embedded in the random volume, their depths were perceived in accordance with their relative disparities. But when the target points were embedded in the sawtooth surfaces their depths were systematically misperceived in a manner predicted by the incorrect depth interpretation of the background points. Rather than seeing a sawtooth pattern, the background points resembled a staircase in depth, and the targets, which appeared embedded in different steps, were misjudged in depth accordingly. The effect suggests a distinction between the depth processing of isolated binocular features and those associated with continuous surfaces.     

Ratings of kinetic depth in multidot displays

Subjects saw kinetic depth displays whose shape (sphere or cylinder) was defined by luminous dots distributed randomly on the surface or in the volume of the object. Subjects rated perceived 3-D depth, rigidity, and coherence. Despite individual differences, all 3 ratings increased with the number of dots. Dots in the volume yielded ratings equal to or greater than surface dots. Each rating varied with 3 of 4 factors (shape, distribution, numerosity, and perspective), but the ratings either between trials or between conditions were often uncorrelated. Object shape affected rigidity but not depth ratings. Veridically perceived polar displays had slightly lower rigidity but higher depth ratings than parallel projection displays. (Reversed polar displays were always grossly nonrigid.) The interaction of ratings and stimulus parameters requires theories and experiments in which different KDE ratings are not treated interchangeably.     

Right hemisphere contribution to lexical access in an aphasic with deep dyslexia

Three hemifield tachistoscopic studies of a right-handed patient with acquired Broca's aphasia and deep dyslexia, but with intact visual fields, are presented to support the hypothesis of right hemisphere (RH) participation in deep dyslexic reading. A systematic comparison of this deep dyslexic with the disconnected RHs of two patients with complete cerebral commissurotomy disclosed a similar, but not identical, pattern of abilities. The results demonstrate partial reliance on the RH for accessing the meaning of single words, but not for phonological encoding in this patient.