Generation of bimanual trajectories of disparate eccentricity: levels of interference and spontaneous changes over practice

The authors examined intermanual interactions of 2 hands that were required to concurrently follow trajectories that differed in eccentricity. Ten healthy participants attempted to learn to trace 2 figures, a circle and an ellipse, with bilaterally isochronous (1:1) timing demands. Initial unimanual trials were followed by bilateral practice comprising 750 movement cycles. Two objectives were addressed: The authors' primary aim was to determine if kinematic interlimb interference is evident independent of spatial and temporal interference and to observe the potential practice-related changes in the nature of that interference. That test was afforded by participants' natural tendency to draw a circle with a relatively constant tangential velocity and an ellipse with a systematically varying velocity. A second aim was to observe the nature of spontaneous changes in the performance of each individual effector, and in the relationship between effectors, across practice. Those objectives were specifically addressed in a context in which augmented feedback was not available to direct the learners' attention to a particular feature of performance. The results suggested that interlimb assimilation of spatial features is the primary source of interference for that task and that apparent effects at the kinematic level are the secondary, indirect product of spatial coupling. Those results were found across blocks of practice. With respect to nondirected performance changes, substantially less improvement was evident in the performance of each individual effector than in the reduction of interlimb interference. Specifically, no practice-related changes in temporal variability or velocity bias, and minimal changes in trajectory smoothness, were evident in individual limbs. Conversely, significant reductions were observed in the variability of relative phase between limbs and in the magnitude of interlimb phase lag.     

How does background information improve memory for text content?

In two experiments, we investigated whether reading background information benefits memory for text content by influencing the amount of content encoded or the organization of the encoded content. In Experiment 1, half of the participants read background information about the issues to be discussed in the text material, whereas half did not. All the participants were then tested for free recall and cued recall of text content. Free recall was greater for individuals who read issue information than for those who did not. The groups did not differ on cued recall, suggesting that background information did not facilitate the encoding of more text content. Measures of representational organization indicated that increased recall in the issue information group resulted from better organization of content in memory. Experiment 2 extended these findings, using background information about text sources, demonstrated that the efficacy of background information depends on the semantic relationship between that information and text content.     

Causal conditional reasoning and semantic memory retrieval: a test of the semantic memory framework

This study tested and refined a framework that proposes a mechanism for retrieving alternative causes and disabling conditions (Cummins, 1995) during reasoning. Experiment 1 examined the relation between different factors affecting retrieval. The test revealed high correlations between the number of possible alternative causes or disabling conditions and their strength of association and plausibility. Experiment 2 explored the hypothesis that due to a more extended search process, conditional inferences would last longer when many alternative causes or disabling conditions were available. Affirmation of the consequent (AC) and modus ponens (MP) latencies showed the hypothesized pattern. Denial of the antecedent (DA) and modus tollens (MT) inferences did not show latency effects. The experiment also identified an effect of the number of disabling conditions on AC and DA acceptance. Experiment 3 measured efficiency of disabler retrieval by a limited time, disabler generation task. As predicted, better disabler retrieval was related to lower acceptance of the MP and MT inferences.     

Psychometric Study of the Child and Adolescent Functional Assessment Scale: Prediction of Contact with the Law and Poor School Attendance

The predictive validity of the Child and Adolescent Functional Assessment Scale (CAFAS) is investigated using the data set generated by the national evaluation of the demonstration service grants funded by the Center for Mental Health Services. Logistic regressions were performed separately for contact with the law and poor school attendance, which were both assessed at 6 months postintake. Other variables included in the model besides the CAFAS total score at intake were age, gender, and family risk factors. The results show that the CAFAS total score at intake was a positive predictor of the likelihood of contact with the law and poor school attendance, even after controlling for age, gender, and risk factors. Furthermore, the CAFAS total score was predictive even after excluding scores on CAFAS subscales, which may have been influenced by absenteeism or delinquency. These findings are consistent with recent research indicating that the CAFAS predicts recidivism in juvenile delinquents.This research was conducted while the author was a Research Associate at the Population Studies Center, University of Michigan, Ann Arbor, MI     

Phonological and articulatory impairment in Alzheimer's disease: a case series

We demonstrate that phonological and articulatory impairments may occur at presentation or early in the course of Alzheimer's disease, contrary to claims that these aspects of language production are relatively preserved until the final stages of this disease. Six patients with pathologically confirmed Alzheimer's disease (AD) and four patients with clinically diagnosed dementia of the Alzheimer's type (DAT) presented with one of five different clinical profiles: nonfluent progressive aphasia, mixed progressive aphasia, progressive aphasia diagnosed as DAT from neuropsychological assessment, initial amnestic syndrome with prominent phonological errors, and biparietal syndrome. Analysis of their conversational speech, single-word production, and performance of highly familiar series speech tasks such as counting revealed false start errors, phonological paraphasias, and/or articulatory difficulty. Neuropathological changes were located in left perisylvian regions consistent with speech and language impairment but atypical for Alzheimer's disease.     

The statistical theory of stepped-up reliability coefficients when a test has been divided into several equivalent parts

This paper is a presentation of the statistical sampling theory of stepped-up reliability coefficients when a test has been divided into any number of equivalent parts. Maximum-likelihood estimators of the reliability are obtained and shown to be biased. Their sampling distributions are derived and form the basis of the definition of new unbiased estimators with known sampling distributions. These unbiased estimators have a smaller sampling variance than the maximum-likelihood estimators and are, because of this and some other favorable properties, recommended for general use. On the basis of the variances of the unbiased estimators the gain in accuracy in estimating reliability connected with further division of a test can be expressed explicitly. The limits of these variances and thus the limits of accuracy of estimation are derived. Finally, statistical small sample tests of the reliability coefficient are outlined. This paper also covers the sampling distribution of Cronbach's coefficient alpha.     

The impact of enhanced incentives on vocational rehabilitation outcomes for dually diagnosed veterans

This study evaluated the efficacy of adding contingency management techniques to vocational rehabilitation (VR) to improve treatment outcome as measured by entry into competitive employment. Nineteen dually diagnosed veterans who entered VR in the Veterans' Administration's compensated work therapy (CWT) program were randomly assigned to CWT (n = 8) or to CWT with enhanced incentives (n = 11). Over the first 16 weeks of rehabilitation, those in the incentives condition could earn up to dollar 1,006 in cash for meeting two sets of clinical goals: (a) remaining abstinent from drugs and alcohol and (b) taking steps to obtain and maintain a competitive job. Results indicate that relative to participants in the CWT-only group, those in the incentives condition engaged in more job-search activities, were more likely to remain abstinent from drugs and alcohol, were more likely to obtain competitive employment, and earned an average of 68% more in wages. These results suggest that rehabilitation outcomes may be enhanced by restructuring traditional work-for-pay contingencies to include direct financial rewards for meeting clinical goals.     

Online attentional-focus manipulations in a soccer-dribbling task: implications for the proceduralization of motor skills

A focus of attention on the step-by-step control of a skill has been shown to be detrimental to experts' performance but to have no significant effect on novices' performance (e.g., S. L. Beilock, T. H. Carr, C. MacMahon, & J. L. Starkes, 2002), contrary to the results of manipulations of the direction of attentional focus (e.g., G. Wulf, M. H?ss, & W. Prinz, 1998). In previous studies, researchers have not separated the focus of attention from the nature of the instruction provided or the skill level of the participants. In the present experiment, 10 skilled and 10 less skilled soccer players dribbled a ball after receiving instructions directing attention to an internal, skill-relevant feature (foot); an internal, skill-irrelevant feature (arm); or a skill-irrelevant task (word-monitoring). Performance was evaluated in relation to a no-attentional-focus control condition. For skilled performers, an internal focus on the arms and feet interfered with performance. For less skilled performers, an internal, yet skill-relevant, focus of attention (foot) did not degrade performance, whereas attention to the arms and word monitoring had a detrimental effect. No significant differences were observed across the three attentional manipulations when the skilled performers used the nondominant foot. The results generally supported the deautomization of skills hypothesis.