Sniffy,the virtual rat: Simulated operant conditioning

We report on the use of our Sniffy program to teach operant conditioning to 900 introductory psychology students. The simulation is designed primarily to teach the principles of shaping and partial reinforcement in an operant chamber. Advanced features are provided for exploring modeling issues and the learning parameters of the model. Students observe the rat’s pretraining behaviors, shape barpressing, and explore the effects of partial reinforcement schedules on a cumulative record. Any of 30 actions can be trained to occur in specific locations in the Skinner box. This paper summarizes details about the software, interface, and instructional objectives.     

Attentional effects on concurrent psychophysical discriminations: Investigations of a sample-size model

In two experiments, a concurrent discrimination paradigm was used to study the effects of visual attention on psychophysical judgments and the consistency of these effects with a sample-size model in which attention influences the variance of the internal representation used to make psychophysical judgments. Two pairs of lines were presented simultaneously—one on each side of fixation—and subjects had to indicate for each pair separately whether or not the lines had the same length. Attention was manipulated by instructing subjects to pay 100%, 75%, 50%, 25%, or 0% of their attention to the discrimination on one side, with the complementary amount of attention to the other side. In the first experiment, the relationship between attention and discrimination accuracy was consistent with the sample-size model both when attentional allocation varied from trial to trial and when it varied between blocks, and the relationship held over more widely varying attentional allocations than had previously been studied. In addition, discriminations were more accurate overall with varied than with blocked attentional allocation, suggesting that the two types of allocation do not merely differ in the degree to which attention is focused. The second experiment examined the effects of attentional allocation and stimulus variance, the latter being manipulated by randomly incrementing or decrementing line lengths. These manipulations had additive effects on total Thurstonian variance, and a version of the samplesize model gave an excellent quantitative fit to the obtained results. Besides supporting the samplesize model, the results of Experiment 2 suggest that criterion variance is at least as large as sensory variance and that criterion but not sensory variance increases with stimulus variance.     

The sampling distribution ofd′

The distribution of sample $\hat d's$ , although mathematically intractable, can be tabulated readily by computer. Such tabulations reveal a number of interesting properties of this distribution, including: (1) sample $\hat d's$ are biased, with an expected value that can be higher or lower than the true value, depending on the sample size, the true value itself, and the convention adopted for handling cases in which the sample $\hat d'$ is undefined; (2) the variance of $\hat d'$ also depends on the convention adopted for handling cases in which the sample $\hat d'$ is undefined and is in some cases poorly approximated by the standard approximation formula, (3) the standard formula for a confidence interval for $\hat d'$ is quite accurate with at least 50–100 trials per condition, but more accurate intervals can be obtained by direct computation with smaller samples.     

Self-management of diabetes mellitus: a critical review

Diabetes has no known cure and is a leading source of morbidity and mortality. Clinical management involves patients managing a complex and variable regimen. This article reviews the determinants of effective self-management and the methods of promoting better self-management. Trait variables (e.g., personality and demographics) have been presumed to affect self-management, but evidence suggests they have little impact. The important determinants of self-management are transient situational factors such as psychological stress and social pressure to eat. Interventions to promote better self-management have reported initial improvements in blood glucose control, but the long-term effects are unclear. We conclude that self-management has been inadequately assessed and that attempts to improve self-management have relied excessively on providing information. More research is needed to clarify determinants of self-management, and interventions to improve self-management will need to change these determinants.     

The self-serving attributional bias: Beyond self-presentation

An experiment was conducted to provide empirical support for the notion that asymmetrical causal attributions for favorable and unfavorable outcomes result from a self-serving attributional bias that occurs independently of self-presentational concerns. Subjects did either well or poorly on an ego-involving test for which their performance, attributions, and evaluations of the test were either public or private. A pattern of self-serving responses for subjects' attributions and evaluations of the test was found in the private conditions, thus providing evidence of the influence of outcome favorability on individuals' perceptions of causality. Theoretical and practical implications of these finding are discussed and suggestions for future research are offered.     

Practice and training in bimanual coordination tasks: strategies and constraints.

There are a number of structural constraints on the coordination of the two hands. Understanding bimanual coordination involves not only identification of these constraints but also how they can be overcome or modulated. The performance of polyrhythms has been used to examine these issues. In this article the constraints on coordination are outlined and research on the acquisition of polyrhythms is reviewed. It is suggested that the constraints on the production of multifrequency ratios are overcome by integrating the timing of the two hands. Oscillator models of coordination are then considered and a two-process model of motor timing is suggested.     

Altruistic Eudaimonism and the Self-Absorption Objection

The Journal of Value Inquiry -