One-Handed Juggling: A Dynamical Approach to a Rhythmic Movement Task

The skill of rhythmically juggling a ball on a racket was investigated from the viewpoint of nonlinear dynamics. The difference equations that model the dynamical system were analyzed by means of local and nonlocal stability analyses. These analyses showed that the task dynamics offer an economical juggling pattern that is stable even for open-loop actuator motion. For this pattern, two types of predictions were extracted: (a) Stable periodic bouncing is sufficiently characterized by a negative acceleration of the racket at the moment of impact with the ball, and (b) a nonlinear scaling relation maps different juggling trajectories onto one topologically equivalent dynamical system. The relevance of these results for the human control of action was evaluated in an experiment in which subjects (N = 6) performed a comparable task of juggling a ball on a paddle. Task manipulations involved different juggling heights and gravity conditions of the ball. The following predictions were confirmed: (a) For stable rhythmic performance, the paddle's acceleration at impact is negative and fluctuations of the impact acceleration follow predictions from global stability analysis; and (b) for each subject, the realizations of juggling for the different experimental conditions are related by the scaling relation. These results permit one to conclude that humans reliably exploit the stable solutions inherent to the dynamics of the given task and do not overrule these dynamics by other control mechanisms. The dynamical scaling serves as an efficient principle for generating different movement realizations from only a few parameter changes and is discussed as a dynamical formalization of the principle of motor equivalence.     

MMPI-Rorschach interrelationships: proposed criteria for evaluating explanatory models

An extensive empirical literature, spanning 50 years and 45 published investigations, leads to the conclusion that the Rorschach and the Minnesota Multiphasic Personality Inventory (MMPI) bear little or no meaningful relationship to each other. An inherent tension exists between these empirical findings and the widespread clinical practice of integrating MMPI and Rorschach results. At least three perspectives have been advanced concerning the relationship between these two instruments. One view holds that variables from the two measures will demonstrate significant patterns of convergence only in carefully designed research studies that involve specific, well-constructed and theoretically derived predictions. A second view postulates that although variables from the Rorschach and MMPI do not bear a high intercorrelation with each other, these variables may be combined to contribute significantly to the prediction of outcome variance. In this view, the combined use of the two instruments yields clinically useful increases in incremental validity not achievable by the use of either instrument in isolation. A third approach is reflected in the proposition that although the MMPI and Rorschach do not produce significant interrelationships under general conditions, meaningful relationships may be yielded under specific psychometric conditions, for example, under conditions in which the response styles are consistently displayed across those two instruments. This article will review research evidence related to each of these perspectives, with particular emphasis on the importance of clearly specifying the criteria to be applied in evaluating these models. The concepts of parsimony and heuristic value are proposed for these evaluation purposes.     

Cognitive-behavioral treatment for professional sexual misconduct among the clergy

Inappropriate sexual behavior by professionals has been reported in increasing numbers. This article focuses on the cognitive-behavioral treatment of clergy who have acted out sexually. Case studies are used to identify the various issues and facets of treatment. The article concludes with a program designed to return previously offending clergy to active roles within their denominations is described.     

Features Resembling Tourette''s Syndrome in Developmental Stutterers

Developmental stuttering (DS) may be related to the extrapyramidal motor system and shares many clinical similarities with Tourette's syndrome (TS), which is widely believed to be associated with extrapyramidal dysfunction. Twenty-two stutterers were examined for neuropsychiatric features commonly seen in TS, including tics, obsessive-compulsive behaviors (OCB), and attention deficit disorders. Eleven stutterers displayed motor tics, and symptoms of OCB were observed at rates similar to those seen in persons with TS. Few stutterers demonstrated significant attentional deficits. Findings are consistent with models suggesting extrapyramidal involvement in DS and raise the possibility that DS and TS are pathogenetically related.     

Appraisals of Child Behavior by Mothers of Problem and Nonproblem Toddlers

Mothers of problem and nonproblem toddlers rated videotapes of their own and unfamiliar children's behavior. They classified the behaviors as positive, negative, or neutral, and evaluated the intensity of the positive or negative behaviors. Ratings did not differ by problem status; however, all mothers classified their own children's behavior as less negative than did an independent observer. Mothers also evaluated all children's negative behavior as less aversive than did the observer. Finally, mothers mistakenly classified less of their own children's behavior as negative and more as positive when compared to their biases in classifying unfamiliar children's behavior.     

Legal and Philosophical Fictions: At the Line Where the Two Become One

Anti-foundationalism is a central topic in recent legal scholarship. The critical legal studies movement (CLS) has mounted a strong challenge to the traditional belief that legal materials (constitutions, statutes, and precedents) determine legal outcomes and constrain judicial decision making. This scholarship has overlooked, however, the degree to which the debate between traditional legal determinacy and anti-foundational indeterminacy is yet another manifestation of a continuous debate in Western thought – one that has its roots in pre-Socratic rhetoric and philosophy.This paper traces the indeterminacy thesis back to the contest of ideas between Protagoras and Plato. I examine two well-known and elated Protagorean notions: first, that two arguments (logoi) are always set in opposition to one another with regard to every matter and, second, that the rhetorician can always make the weaker argument the stronger. I contend that taking these Protagorean notions seriously – perhaps even more seriously than self-avowed anti-foundationalists customarily do – leads paradoxically to a modified endorsement of foundationalism that is nevertheless wholly consistent with the Protagorean project. Calling upon texts by Aristotle, Seneca and René Girard, I focus upon how fictionality in representations of Platonically conceived Truth reveals a binarization in thought that is simultaneously untenable and unavoidable.     

Racial Categorization and Stereotype-Based Judgments About Homeless People1

The present study uses a social-cognitive paradigm to examine the association between racial categorization and stereotype-based judgments about homeless people. The study uses data from a national White subsample (N= 1,221) surveyed about attitudes toward homeless/homeless mentally ill people. It was hypothesized that individual differences in perceptions of the representativeness of Blacks in the homeless population, as measured by subjective estimates of the percentage of Blacks, would be associated with the enhancement of racially relevant negative stereotypes about homeless people. A secondary hypothesis was that perceptions of the representativeness of Blacks would be more strongly associated with the stereotype of homeless people as dangerous than with the view of them as lazy. The results support these hypotheses.     

An Evaluation of the Health Belief Model for Predicting Perceived and Actual Dietary Quality1

The health belief model was evaluated for its ability to predict perceived and actual dietary quality. The assessment relied upon data collected from 1,502 respondents by the US. Department of Agriculture in its 1991 Continuing Survey of Food Intakes by Individuals and the Diet and Health Knowledge Survey. The health belief model provided good prediction of perceived dietary quality, but provided moderate to weak prediction of 7 measures of actual dietary quality that were calculated from food intake records. Implications are suggested for using the health belief model to understand the determinants of dietary quality.     

Personal Theories of Hunger and Eating1

Recent research on hunger and eating has shown that (a) among individuals with adlibitum access to food, hunger and eating are not regulated by deviations in the body's energy resources from set-points, and (b) it is healthier for people to consume their daily caloric intake as several small snacks than as 3 large meals. People's beliefs about hunger and eating were assessed in 2 questionnaire studies. In Study 1, a large sample of undergraduates was surveyed; in Study 2, dietetics students, nursing students, medical students, dietitians, nurses, and doctors were surveyed. Both studies revealed that people's personal theories of hunger and eating were inconsistent with research findings in ways that could promote overconsumption. These results suggest that educational programs designed to modify the beliefs about hunger and eating of people suffering from problems of overconsumption and of health professionals who treat problems of overconsumption may increase the effectiveness of current treatment regimens.