Bivar: A program for generating correlated random numbers

This article describes Bivar, a program that generates random numbers from a wide variety of bivariate distributions. Numbers are written to an ASCII output file, from which they can be read as needed by programs simulating stochastic processes. The program runs under the DOS operating system on IBM-PC compatibles with a 386 or later processor, and it is free for educational and noncommercial use.     

A simple behavioral treatment program for psychogenic encopresis

A treatment program based on behavioral psychological principles which can be explained to parents in one session and supervised by letters and phone calls each week was found to be highly effective in completely eliminating the problem of psychogenic encopresis. A controlled study and extensive clinical use have indicated 100% effectiveness for the program when carefully adhered to.     

Tracking simple and complex sequences

We address issues of synchronization to rhythms of musical complexity. In two experiments, synchronization to simple and more complex rhythmic sequences was investigated. Experiment 1 examined responses to phase and tempo perturbations within simple, structurally isochronous sequences, presented at different base rates. Experiment 2 investigated responses to similar perturbations embedded within more complex, metrically structured sequences; participants were explicitly instructed to synchronize at different metrical levels (i.e., tap at different rates to the same rhythmic patterns) on different trials. We found evidence that (1) the intrinsic tapping frequency adapts in response to temporal perturbations in both simple (isochronous) and complex (metrically structured) rhythms, (2) people can synchronize with unpredictable, metrically structured rhythms at different metrical levels, with qualitatively different patterns of synchronization seen at higher versus lower levels of metrical structure, and (3) synchronization at each tapping level reflects information from other metrical levels. The latter finding provides evidence for a dynamic and flexible internal representation of the sequence's metrical structure.     

A context-sensitive representation of word meanings

This study provides a numerical representation of contextual effects on the meanings of words, constructed from the order judgments of 19 subjects concerning the word "red" in 19 sentences. Subjects judged whether or not the red object mentioned in a sentence was redder than, less red than, or could be equally as red as the red object mentioned in each of the other sentences. These judgments were well described as an interval order. This means that the red ascribed in a sentence can be represented by a real interval with judgments of equally red corresponding to overlapping intervals. Semiorder axioms were not met, indicating that the width of the interval varied from sentence to sentence. Possible ways of incorporating the result into theories of semantic memory were discussed, as well as ways of accounting for the pronounced individual differences which were observed. The research described herein was supported by the National Institute of Education under Contract HEW NIE-G-74-0007.     

A program to construct stimulus sequences for controlled lag recognition memory experiments

Experimental designs in recognition memory research frequently employ a continuous sequence of trials in which each stimulus item is presented on two separate occasions. Subjects are required to indicate for each item whether it is new (first presentation) or old (second presentation), and the lag between the first and second presentation is manipulated as a variable in the design. In order to take advantage of the power and efficiency of this procedure, it is necessary to construct sequences that contain the desired set of intervening lags, while leaving no unproductive gaps in the sequence. Furthermore, in order to reduce confounding due to sequential effects, it is desirable to block experimental conditions within subsections of the sequence. Thisfortran program obviates the labor involved in devising such sequences by automating the process of construction.     

Conjunction of a programming language and text formatter for generating randomized questionnaires

The conjunction of a progamming language and a text formatter is described as an aid to the construction of questionnaires in which the order of presentation of items is randomized and the output has a neat and professional appearance. The technique has marked advantages over the use of a programming language on its own. Modifications can be easily and independently made in the format of the document or in the experimental procedure itself, for example, number or type of questionnaire items, or instructions. The particular example is for BASIC and RUNOFF, but the technique would generalize to other language-formatter pairs available on computers of any size.     

A simple BASIC program to generate values for variable-interval schedules of reinforcement

A BASIC program to generate values for variable-interval (VI) schedules of reinforcement is presented. A VI schedule should provide access to reinforcement with a constant probability over a time horizon. If the values in a VI schedule are calculated from an arithmetic progression, the probability of reinforcement is positively correlated with the time since the last reinforcer was delivered. Fleshler and Hoffman (1962) developed an iterative equation to calculate VI schedule values so that the probability of reinforcement remains constant. This easy-to-use program generates VI schedule values according to the Fleshler and Hoffman equation, randomizes the values, and saves the values in ASCII to a disk file.     

Determining the sample size for a replication attempt: A short and simple microcomputer program

Replication studies frequently fail to detect genuine effects because too few subjects are employed to yield an acceptable level of power. To remedy this situation, a method of sample size determination in replication attempts is described that uses information supplied by the original experiment to establish a distribution of probable effect sizes. The sample size to be employed is that which supplies an expected power of the desired amount over the distribution of probable effect sizes. The method may be used in replication attempts involving the comparison of means, the comparison of correlation coefficients, and the comparison of proportions. The widely available equation-solving program EUREKA provides a rapid means of executing the method on a microcomputer. Only ten lines are required to represent the method as a set of equations in EUREKA’s language. Such an equation file is readily modified, so that even inexperienced users find it a straightforward means of obtaining the sample size for a variety of designs.     

RAP: A computer program for exploring similarities in behavior sequences using random projections

A computer program (RAP, for random projection) for exploring similarities between and within sequences of behavior is presented. Given a time window of a sequence, the program calculates a signature, a real-valued vector that is a random projection of the contents of the window (i.e., the codes occurring within it and their relative location, or onset and offset times) into an arbitrary K-dimensional space. Then, given two different time windows from the same sequence or from different sequences, their similarity is computed as an inverse function of the Euclidean distance between their respective signatures. By defining moving (overlapped or not overlapped) windows along each sequence and calculating similarities between every pair of windows from the two sequences, a map of similarities or possible recurrent patterns is obtained; the RAP program represents them as gray-level lattices, which are displayed as mouse-sensitive images in an HTML file. Computation of similarities is based on the random projection method, as presented by Mannila and Seppänen (2001), for the analysis of sequences of events. The program reads sequence data files in Sequential Data Interchange Standard (SDIS) format (Bakeman &; Quera, 1992, 1995a).