Anticipatory control of postural and task muscles during rapid arm flexion

A multicomponent pattern of premovement (anticipatory) activity in both task and postural muscles was examined for a unilateral rapid arm flexion movement (Belen'kii, Gurflnkel, & Pal'tsev, 1967) performed under simple visual reaction-time conditions. Subjects performed 30 right- and 30 left-side responses on each of four consecutive days. The anticipatory postural muscle activity may be considered a valid component of voluntary unilateral arm flexion. Invariances and variability in the spatial and temporal characteristics of the neuromuscular pattern are described in relationship to behavioral and motor control models of response organization. It is suggested that some temporal patterning among response components may not be preprogrammed centrally.     

Videotaping effects on the behaviors of low income mothers and their infants during floor-play interactions

Interaction behaviors and language measures of low income mothers and their 12-month-old infants were compared for floor-play situations in which the mother was aware and unaware of being videotaped. When the mothers were aware of being videotaped, they were more proximal to their infants, offered and demonstrated toys more frequently, engaged in more frequent interaction games, vocalized more frequently, emitted a greater number of words as well as declarative and imperative utterances, and their infants engaged in more constructive play. Combining the analysis of variance and correlational analyses results suggested that the verbal behaviors of mothers were inflated and their non-verbal behaviors were distorted when they were aware of being videotaped. The implications of these data for the use of videotaping as an assessment and intervention tool are discussed.     

A bayesian approach to confirmatory factor analysis

Confirmatory factor analysis is considered from a Bayesian viewpoint, in which prior information on parameter is incorporated in the analysis. An iterative algorithm is developed to obtain the Bayes estimates. A numerical example based on longitudinal data is presented. A simulation study is designed to compare the Bayesian approach with the maximum likelihood method.Computer facilities were provided by the Computer Services Center, The Chinese University of Hong Kong.     

Two logit models for external analysis of preferences

A logit vector model and a logit ideal point model are presented for external analysis of paired comparison preference judgments aggregated over a homogeneous group. The logit vector model is hierarchically nested within the logit ideal point model so that statistical tests are available to distinguish between these two models. Generalized least squares estimation procedures are developed to account for heteroscedastic sampling error variances and specification error variances. Two numerical illustrations deal with judgments concerning employee compensation plans and preferences for salt and sugar in the brine of canned green beans.     

FUNCTIONAL ASSESSMENT,CURRICULAR REVISION,AND SEVERE BEHAVIOR PROBLEMS

An adolescent female with multiple handicaps and a long history of severely disruptive behavior participated in a functional assessment linked directly to specific revisions in her school curriculum. During Phase 1, reversal designs were used to test hypotheses pertaining to antecedent and auricular influences on problem behavior. During Phase 2, a multiple baseline across afternoon and morning time periods demonstrated that the auricular revisions were effective in eliminating severely disruptive behavior and increasing on-task responding. Data also showed that inappropriate “psychotic” speech was reduced and appropriate social interactions were increased. Follow-up results showed that the changes were maintained throughout the school year. Questionnaire data provided social validation of the procedures and outcomes. The findings are discussed in relation to their implications for functional assessment, individualized curricula, and positive programming for students with disabilities and serious behavior problems.     

Black Students' Reactions to Feedback Conveyed by White and Black Teachers1

The present investigation examined some processes mediating self-fulfilling prophecies among black students. Specifically, we hypothesized that feedback conveyed by black and white teachers would differentially influence black students' perceptions of how the teacher viewed their success/failure, effort, ability, luck and task difficulty. In addition, we hypothesized that negative feedback would affect perceptions of evaluations differently than positive feedback. Ninety black undergraduates participated in an experiment in which a black or white teacher (confederate) expressed one of five evaluative feedback responses to a student's score on an analogies test. The results provided partial support for the first hypothesis: black female students perceived white teachers as assessing their performance less positively: that is, they perceived them to underestimate their ability and the difficulty of the task. Negative feedback also led students to believe the teacher held an unfavorable but inaccurate impression of their ability and effort, and that the teacher underestimated the difficulty of the task. These findings suggest that black students—black females in particular—may assume that white teachers hold less favorable assessments of them than black teachers and all students may be sensitive to negative evaluations.