The effect of light intensity when onset or termination of illumination is used as reinforcing stimulus

The Psychological Record - Two experiments were performed to examine the reinforcing effects of onset and termination of non-aversive illumination, made conterminous with lever contacting, as a...     

A statistical description of verbal learning

Free-recall verbal learning is analyzed in terms of a probability model. The general theory assumes that the probability of recalling a word on any trial is completely determined by the number of times the word has been recalled on previous trials. Three particular cases of this general theory are examined. In these three cases, specific restrictions are placed upon the relation between probability of recall and number of previous recalls. The application of these special cases to typical experimental data is illustrated. An interpretation of the model in terms of set theory is suggested but is not essential to the argument.     

The factorial interpretation of test difficulty

This paper discusses the influence of test difficulty on the correlation between test items and between tests. The greater the difference in difficulty between two test items or between two tests the smaller the maximum correlation between them. In general, the greater the number of degrees of difficulty among the items in a test or among the tests in a battery, the higher the rank of the matrix of intercorrelations; that is, differences in difficulty are represented in the factorial configuration as additional factors. The suggestion is made that if all tests included in a battery are roughly homogeneous with respect to difficulty existing hierarchies will be more clearly defined and meaningful psychological interpretation of factors more readily attained.     

Decision time,subjective probability,and task difficulty

This study analyzed the relationships between decision time, subjective probability, and task difficulty in the context of a probability assessment task involving memory search. The results indicate that decision time and subjective probability do not yield identical functions. Also, decision time increases as subjective task difficulty increases. A similar relationship obtains between decision time and a measure of objective task difficulty. These latter two findings are inconsistent with Hogarth’s (1975) prediction of a nonmonotonic relationship between decision time and task difficulty.     

Presidential Inflexibility and Veto Behavior: Two Individual-Situational Interactions

ABSTRACT The suitable personality traits for optimal leadership may depend on the type of leadership, the criterion of leader effectiveness, and various situational constraints This point was illustrated via the specific area of presidential leadership The working relationship between the Chief Executive and Congress, as defined by regular vetoes and vetoes overturned, provided the criterion variables for a congressional time-series analysis (N= 99) of all 39 American presidents The impact of a single personality attribute, presidential inflexibility, was examined in the context of several variables suggested by past research The relation between inflexibility and willingness to exploit the regular veto varied according to the incumbent's electoral mandate, while the association between inflexibility and the propensity of Congress to override a veto depended on the extent to which the president's party controlled Congress—this last interaction was labeled the Johnson-Wilson effect In the context of the person-situation debate, these findings illustrate how certain situations can determine whether, and to what degree, a stable individual attribute will have behavioral manifestations     

Methylphenidate in hyperactive children: Differential effects of dose on academic,learning, and social behavior

Methylphenidate (Ritalin) has been shown to have differential effects on hyperactive children's behavior as a function of dose level. In the present investigation, a triple-blind, placebo-control, within-subject (crossover) experimental design was employed in which 12 hyperactive boys between 6 and 10 years received three different dosages of methylphenidate (5, 10, and 15 mg) in a randomly assigned sequence. Dosage effects were assessed on clinic(PAL-Paired Associates Learning test) and school-(percent on task, teacher ratings, work completion rates, and accuracy) related behaviors. For 10 of the children, classified as responders to medication by the PAL using the criteria of Swanson, Kinsbourne, and colleagues, a series of ANCOVAs with repeated measures showed significant dosage effects on teacher ratings (p 01), percent on task (p 01), academic accuracy (p 05), and assignment completion rates (p 05). PAL performance was also significantly enhanced (p 01) after optimal dose levels were considered. Subsequent trend analysis showed a significant positive linear relationship between dose and each of the dependent variables. A comparison of fixed-dose and miligram-per-kilogram plots showed that children's performance across the different dosages were clearly individualistic and task-specific, even when similar body weights were compared. The implications of using clinic-based testing to determine optimal medication responsivity were discussed.We would like to express our sincere appreciation to the following pediatricians for their valuable assistance: W. H. McDermott, D. J. Chronley, R. B. Trivett, F. J. Jehle, P. M. Small, and F. T. Leong. Grateful acknowledgement is also extended to the two anonymous reviewers whose comments contributed to the content of this paper, and to the undergraduate and graduate student members of the Children's Learning Clinic.