A new interpretation of stochastic test models

A new look at latent trait models is proposed. The event of an item being solved by a person is related to the event that the momentary value of a person-specific random component is at least as large as the corresponding value of an item-specific random component. The Birnbaum logistic test model is shown to be generated by a bivariate extreme value distribution for the components. Some consequences of this interpretation are outlined.I am indebted to David Strauss for calling the extreme value distribution (1) to my attention in a random utility context. The paper also benefited from discussions with H. C. Micko, H. H. Schulze and K. F. Wender.     

Effects of d-amphetamine and cocaine on strained ratio behavior in a repeated-acquisition task.

Pigeons acquired a different four-response chain each session by responding sequentially on three keys in the presence of four colors. When the fixed-ratio requirement for food presentation was five completions of the chain, d-amphetamine and cocaine disrupted the behavior. As the dose of each drug was increased, the overall response rate decreased, the overall accuracy was impaired (i,e., percent errors increased), and there was less within-session error reduction (acquisition). In contrast, when the fixed-ratio requirement was either 20 or 50 completions of the chain, certain doses of both drugs produced large increases in the overall response rate by eliminating the extended pausing (ratio strain) that was characteristic of the control sessions. These rate-increasing effects were accompanied by error-decreasing effects, both during acquisition and after the response chain had been acquired. Taken together, the results show that the effects of d-amphetamine and cocaine on behavior in a repeated-acquisition task can be modulated by manipulating the value of the fixed-ratio schedule maintaining the behavior.     

Punishment of responding under schedules of stimulus-shock termination: effects of d-amphetamine and pentobarbital.

Responding maintained in squirrel monkeys under 5-min fixes-interval schedules of either food presentation or termination of a visual stimulus associated with electric-shock delivery was suppressed by presenting an electric shock for every thirtieth response (punishment). In monkeys responding under the schedule of food presentation, d-amphetamine sulfate only further decreased punished responding, and pentobarbital sodium markedly increased punished responding, as expected from previous reports. In monkeys responding under the schedule of stimulus-shock termination, however, the effects of the two drugs were opposite: d-amphetamine markedly increased punished responding, whereas pentobarbital only decreased responding. Thus, the effects of these drugs on punished responding were different depending on the type of event maintaining responding. These and previous results indicate that it may be misleading and inaccurate to speak of the effects of drugs on "punished responding" as though punishment were a unitary phenomenon. As with any behavior, the effects of drugs and other interventions on punished responding cannot be accurately characterized independently of the precise conditions under which the behavior occurs.     

THE EFFECTS OF DIFFERENT REINFORCEMENT CONDITIONS ON THE TEST PERFORMANCE OF MULTIHANDICAPPED DEAF CHILDREN1

The present study explored the effects of different reinforcement conditions on the number of correct responses on the Raven Progressive Matrices. Four groups of 11- to 18-year-old multihandicapped deaf children matched on the basis of mean age and pretest scores were used. The groups were randomly assigned to any of four posttest conditions: end-of-session reinforcement, noncontingent reinforcement, delayed reinforcement, and immediate reinforcement. The mean posttest score of subjects tested under the immediate-reinforcement condition was significantly higher than that of any other group. No significant differences were observed between the mean posttest scores of the three other groups. The practical implications of using reinforcement procedures for testing purposes are discussed.     

Switching from competition to sharing or cooperation at large response requirements: competition requires more responding

Two pairs of high-school students matched-to-sample for money. On each trial, a subject could either respond on one lever to take the matching-to-sample problem himself (taking response) or respond on a second lever to give the problem to his coactor (giving response). The first subject to complete the response requirement determined the distribution of the problem. Competition maximizes the amount of responding over trials, i.e., both subjects make taking responses on each trial. Sharing and cooperation minimize responding: only one subject makes a taking response (sharing) or a giving response (cooperation) on each trial, and the subjects alternate responding such that there is an equitable distribution of responses and reinforcers over trials. Large increases in the fixed-ratio response requirement to distribute problems produced: (1) a switch from competition to sharing or cooperation, (2) the expected concomitant change from inequitable to equitable distributions of reinforcers, and (3) a reduction in the amount of responding for three of the four subjects. Previous animal research has shown that large response requirements may have aversive properties. Switching from competition to sharing or cooperation at large response requirements allows a reduction in responding and, at the same time, a moderate number of reinforcers for each subject.     

Preference between variable-ratio and fixed-ratio schedules: local and extended relations.

Although it has repeatedly been demonstrated that pigeons, as well as other species, will often choose a variable schedule of reinforcement over an equivalent (or even richer) fixed schedule, the exact nature of that controlling relation has yet to be fully assessed. In this study pigeons were given repeated choices between concurrently available fixed-ratio and variable-ratio schedules. The fixed-ratio requirement (30 responses) was constant throughout the experiment, whereas the distribution of individual ratios making up the variable-ratio schedule changed across phases: The smallest and largest of these components were varied gradually, with the mean variable-ratio requirement constant at 60 responses. The birds' choices of the variable-ratio schedule tracked the size of the smallest variable-ratio component. A minimum variable-ratio component at or near 1 produced strong preference for the variable-ratio schedule, whereas increases in the minimum variable-ratio component resulted in reduced preference for the variable-ratio schedule. The birds' behavior was qualitatively consistent with Mazur's (1984) hyperbolic model of delayed reinforcement and could be described as approximate maximizing with respect to reinforcement value.     

Observed-score equating as a test assembly problem

A set of linear conditions on item response functions is derived that guarantees identical observed-score distributions on two test forms. The conditions can be added as constraints to a linear programming model for test assembly that assembles a new test form to have an observed-score distribution optimally equated to the distribution on an old form. For a well-designed item pool and items fitting the IRT model, use of the model results into observed-score pre-equating and prevents the necessity ofpost hoc equating by a conventional observed-score equating method. An empirical example illustrates the use of the model for an item pool from the Law School Admission Test.The authors are most indebted to Norman D. Verhelst for suggesting Proposition 4 and its proof, to the Law School Admission Council (LSAC) for making available the data set, and to Wim M. M. Tielen for his computational assistance.     

Tests for linear trend in the smallest eigenvalues of the correlation matrix

A test for linear trend among a set of eigenvalues of a correlation matrix is developed. As a technical implementation of Cattell's scree test, this is a generalization of Anderson's test for the equality of eigenvalues, and extends Bentler and Yuan's work on linear trends in eigenvalues of a covariance matrix. The power of minimumx ² and maximum likelihood ratio tests are compared. Examples show that the linear trend hypothesis is more realistic than the standard hypothesis of equality of eigenvalues, and that the hypothesis is compatible with standard decisions on the number of factors or components to retain in data analysis.This work was supported by National Institute on Drug Abuse Grants DA01070 and DA00017. The assistance of Maia Berkane and several anonymous reviewers is gratefully acknowledged.     

Gender and projective imagination of threat in achievement and affiliation situations

In a study by Pollak and Gilligan (1982) where fantasies of violence were seen as indicative of perception of danger, women responded with more violent imagery to situations of achievement, whereas men responded with more violent imagery to affiliation situations. This indicates gender differences in motivational needs, which corresponds to modern gender development theories (e.g., Chodorow, 1978). In the present studies, the hypotheses that women fear achievement situations whereas men fear situations of affiliation were tested on Swedish samples totaling 44 men and 47 women. In Study 1, the hypothesis that violent imagery correlates with affiliation themes in the stories written by men was partly supported, whereas the hypothesis that violent imagery would be highly correlated with achievement themes in the stories written by women was not confirmed. In Study 2, no support was obtained for the hypotheses. In sum, contrary to previous studies, no substantial support was obtained for the hypothesis that women connect violent imagery with achievement situations, whereas some evidence was found for the hypothesis that men construe danger as arising from affiliation situations. The greater incidence of violence in men’s fantasy reported in previous studies was not supported in either of the two studies. The results are discussed in the context of cross-cultural differences.