Reinforcement,stereotypy, and rule discovery

The effects of reinforced pretraining on subsequent rule discovery were examined with college students as subjects. Levels of behavioral stereotypy observed during reinforced and non-contingent pretraining were compared. During pretraining subjects received reinforcement if they pressed two keys in a particular sequence. During the problem session pressing each key four times was a necessary condition for reinforcement, but each problem had additional different requirements for reinforcement. Subjects were asked to solve the problems by discovering the rule that determined whether or not they received reinforcement. Levels of stereotyped responding during pretraining were equivalent for contingently and non-contingently trained subjects. During the problem session contingently pretrained, non-contingently pretrained, and naive subjects required equal numbers of trials to solve problems and solved the same number of problems. The results suggest that behavioral stereotypy observed in this experimental preparation may be due to repeated exposure to the task. Differences between the results observed in this study and that of Schwartz (1982) and implications for the use of reinforcement procedures in applied settings are discussed.

     

Higher order moments of order statistics from INID symmetric random variables

In this paper we present analogues of Balakrishnan's (1989) relations that relate the triple and quadruple moments of order statistics from independent and nonidentically distributed (I.NI.D.) random variables from a symmetric distribution to those of the folded distribution. We then apply these results, along with the corresponding recurrence relations for the exponential distribution derived recently by Childs (2003), to study the robustness of the Winsorized variance.     

A changed America? The effects of September 11th on depressive symptoms and alcohol consumption

In the weeks following the terrorist attacks of September 11, 2001, social commentators argued that America had profoundly "changed." In light of these arguments and the literature on disasters, we examine the immediate and longer-term mental health consequences of September 11th using a national sample of full-time American workers. We model the effects of temporal proximity to the attacks on depressive symptoms and alcohol consumption, while controlling for demographic characteristics. Our data revealed a significant increase in the number of depressive symptoms reported during the 4 weeks after the attacks. In the subsequent weeks, levels of depressive symptoms returned to pre-September 11th levels. Contrary to expectations, there was some indication of decreased alcohol consumption after September 11th, although these effects were modest. These analyses provide little support for popular assertions that September 11th resulted in lasting and measurable impacts on Americans' well-being.     

Do expressive mothers have expressive children? The role of socialization in children's affect expression

The effects of maternal expressiveness and children's gender on children's nonverbal expressiveness were assessed in two settings. In the laboratory, 30 boys and 30 girls of kindergarten age were unobtrusively videotaped while talking about happy, sad, and fearful experiences and while experiencing three social situations designed to elicit happy, disappointed, and apprehensive feelings. Videotapes were rated for emotion expression, using global ratings and EMFACS codes. In school, teachers rated these children's expression of four discrete emotions. In both the laboratory and school settings children were more positively expressive than negatively so, and positive and negative expressiveness were unrelated. In the laboratory children's positive expressiveness was consistent across the three social situations, but negative expressiveness varied across affective context. In both settings, children of low-expressive mothers were more positively expressive than children of high-expressive mothers, who tended to be more negatively expressive than children of low-expressive mothers. The difference in negative expression appeared most striking for anger. Gender was not predictive of children's expressiveness in either setting     

Unification of Dirichlet Methodology

In this article we provide a unified framework for solving Dirichlet related probability and waiting time problems. We consider a Pólya sampling scheme in which each time an object is selected, it is put back into the population along with c additional objects of the same type. By considering both fixed sample size and inverse sampling procedures, we unify the Dirichlet I, J, C, and D functions with their hypergeometric counterparts by extending these functions to Pólya sampling. We then use these functions to unify and extend the corresponding expected waiting time results.     

Probability computations for an extension of the geometric distribution

An extension of the stochastic process associated with the geometric distribution is presented. Combinatorial arguments are used to derive probabilities for various events of interest. Probabilities are approximated by evaluating truncated series. Bounds on the errors of approximation are developed. An example is presented and some additional applications are noted.     

The Transformative Potential of Experience: Learning,Group Dynamics,and the Development of Civic Virtue in a Mobile Soup Kitchen

VOLUNTAS: International Journal of Voluntary and Nonprofit Organizations - Civic engagement has long been understood as a transformative activity, conducive to the reformation of individual...     

Ambivalent economizations: the case of value added modeling in teacher evaluation

Theory and Society - Research on economization processes is increasingly taking seriously the social and material processes through which various policy domains are transformed into economic...