Wise: Web Interface for Statistics Education

The Web Interface for Statistics Education (WISE) project includes a World-Wide Web site to support the teaching of introductory social-science statistics courses. The site provides easy access to data bases, archived discussion lists, electronic journals, links to other sites focused on relevant statistics topics, and it includes a prototype of an on-line tutorial. The tutorial, which is the focus of the current paper, is designed to capitalize on special capabilities offered by the Web. The easy linkage between Web pages provides support for a highly interactive tutorial, which uses “failure-based” learning and immediate feedback. Students rated the tutorial as easy to use and indicated that it would have improved their initial statistics course.     

Computer program for quasi-random stimulus sequences with equal transition frequencies

C language routines are presented for the generation of randomized stimulus sequences constructed from multiple presentations of m stimuli satisfying sequential constraints with respect to the frequencies of the occurrence of n-gram subsequences. Applications are suggested for sequential experiments in which main effects for the present stimulus and the stimuli in the preceding (n?1)-length substring can be tested, as well as the interactions among stimuli at the various positions in the substrings.     

Fixed and optional stopping models for two-choice discrimination times

Several current models for choice- or discrimination-time experiments represent the stimulus as a sequence of independent and identically distributed observations. This paper develops and compares models based on two different stopping rules that a subject might use to terminate his sampling process and convert his perceptual evidence into an observable response. The fixed and optional stopping rules yield different predicted forms for the speed/accuracy tradeoff function and for the relation between mean and variance of response times. These predictions are developed in the general case and then specialized for certain conditions of symmetry, so that the expressions are easier to apply and to compare between models. A later section considers how changes in stopping criteria (either between or within experimental trials) affect predictions about mean response times for correct responses and errors, and then uses these ideas to relate the optional stopping rule for the Random Walk models to those of the Accumulator models. A final section considers specialized models for stimulus detection and intensity discrimination that assume Poisson-distributed sensory input, and relates these models to the present fixed stopping model.     

Reaction time to the onset and offset of electrocutaneous stimuli as a function of rise and decay time

Reaction times were obtained to the onset and offset of 70-cps electrocutaneous signals of five rise and decay times and five intensity levels. The results show that both onset and offset RTs increase linearly with increased rise and decay times. With fast rates of rise or decay, the onset produces faster RTs than the cessation of stimulation. The opposite effect is found when long rise and decay times are used. Interpretations of these results are given in terms of neural adaptation and accommodation.     

Reaction time to the onset and offset of electrocutaneous stimuli as a function of rise and decay time

Reaction times were obtained to the onset and offset of 70-cps electrocutaneous signals of five rise and decay times and five intensity levels. The results show that both onset and offset RTs increase linearly with increased rise and decay times. With fast rates of rise or decay, the onset produces faster RTs than the cessation of stimulation. The opposite effect is found when long rise and decay times are used. Interpretations of these results are given in terms of neural adaptation and accommodation.