Proofs,Grounds and Empty Functions: Epistemic Compulsion in Prawitz’s Semantics

Journal of Philosophical Logic - Prawitz has recently developed a theory of epistemic grounding that differs in many respects from his earlier semantics of arguments and proofs. An innovative...     

Undermining the Zeigarnik effect: Another hidden cost of reward

Forty college students participated in a study ostensibly designed to obtain measures of the hemispheric activity while they worked on a spatial reasoning task. In fact, our true interest was in determining whether subjects would return to the spatial reasoning task once the hemispheric recordings were completed. Subjects would normally be expected to return to the task by virtue of the Zeigarnik effect because no subject completed the task during the “hemispheric recording” phase. The manipulation involved telling one group of subjects that they would be paid $1.50 for participating in the study (expected reward group). The remainder of the subjects were not led to expect the reward (unexpected reward group). The result was that 86% of the unexpected reward subjects but only 58% of the expected reward subjects (p < .05) manifested the Zeigarnik effect. This differential tendency to return to the task was further reflected in time differences. The average unexpected reward subject spent 3 min 48 sec of a five-minute free-choice period at the task, whereas the average expected reward subject spent only 2 min 20 sec (p < .05). Reward expectancy, therefore, led to an undermining of the Zeigarnik effect. This observation supports Condry's prediction that rewarding performance at a task can lead to premature task disengagement.     

Response competition effects insame-different judgments

An account ofsame-different discriminations that is based upon a continuous-flow model of visual information processing (C. W. Eriksen & Schultz, 1979) and response competition and inhibition between the responses by which the subject signifies his judgment is presented. We show that a response signifyingsame will on the average be executed faster due to less priming or incipient activation of the competing response,different. In the experiment, the subjects matched letters on the basis of physical identity. The degree of priming ofdifferent responses on same trials and ofsame responses ondifferent trials was manipulated by an extraneous noise letter placed in the display. Latency for judgments onsame trials increased as the feature overlap of noise and target letters decreased. Latencies were shorter ondifferent trials when the noise letter was dissimilar to either target letter than when the noise letter was the same as one of the targets. These results were consistent with the response-competition interpretation.     

Bidirectional Links Between Teachers’ Disciplinary Practices,Students’ Peer Status,and Students’ Aggression in Kindergarten

Research on Child and Adolescent Psychopathology - This study examined bidirectional links between teachers’ disciplinary practices (punitive and educational), students’ peer status in...     

Proving quadratic reciprocity: explanation,disagreement, transparency and depth

Gauss’s quadratic reciprocity theorem is among the most important results in the history of number theory. It’s also among the most mysterious: since its discovery in the late eighteenth century, mathematicians have regarded reciprocity as a deeply surprising fact in need of explanation. Intriguingly, though, there’s little agreement on how the theorem is best explained. Two quite different kinds of proof are most often praised as explanatory: an elementary argument that gives the theorem an intuitive geometric interpretation, due to Gauss and Eisenstein, and a sophisticated proof using algebraic number theory, due to Hilbert. Philosophers have yet to look carefully at such explanatory disagreements in mathematics. I do so here. According to the view I defend, there are two important explanatory virtues—depth and transparency—which different proofs (and other potential explanations) possess to different degrees. Although not mutually exclusive in principle, the packages of features associated with the two stand in some tension with one another, so that very deep explanations are rarely transparent, and vice versa. After developing the theory of depth and transparency and applying it to the case of quadratic reciprocity, I draw some morals about the nature of mathematical explanation.

     

Nonsuicidal Self-injury,Suicide Planning,and Suicide Attempts Among High-risk Adolescents Prior to Psychiatric Hospitalization

Research on Child and Adolescent Psychopathology - The purpose of this study was to understand the trajectories of nonsuicidal self-injury (NSSI) and suicide plans (SP) in the 90&nbsp;days...     

Gamma is a Measure of the Accuracy of Predicting Performance on One Item Relative to Another Item,not of the Absolute Performance on an Individual Item Comments on Schraw (1995)

The recent paper by Schraw ( Measures of feeling-of-knowing accuracy: a new look at an old problem , Applied Cognitive Psychology, 1995, 9, 321—332) is flawed by several inaccuracies and by Schraw's failure to distinguish between two fundamentally different aspects of the accuracy of metacognitive predictions: (1) calibration (aka absolute accuracy, defined in terms of whether the predicted value assigned to a single item is followed by the occurrence of that value on the criterion test), and (2) resolution (aka relative accuracy, defined in terms of whether the predicted performance on one item relative to another item is followed by the occurrence of that ordering of the two items on the criterion test). Because of these (and other) problems, his recommendations seem misleading and counterproductive.