The effect of signaled reinforcement availability on concurrent performances in humans

During Phase I, three female human subjects pressed a button for monetary reinforcement in two-component concurrent variable-interval schedules. Five different reinforcement frequencies were used in component A, whereas the reinforcement frequency in component B was held constant. Absolute rates of responding conformed to equations proposed by Herrnstein to describe concurent performances, and the ratios of the response rates and the times spent in the two components conformed to the matching law. During Phase II, the availability of reinforcement in component A was signaled by the illumination of a lamp. This resulted in suppression of response rates in component A and elevation of response rates in component B, these changes being reflected in a distortion of the matching relationship which took the form of a bias in favor of component B.     

IMPROVING THE GENERALIZED MNEMONIC PERFORMANCE OF A DOWN'S SYNDROME CHILD1

A training program was conducted to improve the generalized mnemonic performance, or memory, of a Down's Syndrome child. Training was directed at digit-span performance with generalization from training determined by responses to untrained mnemonic performance probes. The digit-span items varied in length from three to five digits. Each length constituted an item class, with each class trained within the framework of a multiple-baseline design. Probes consisted of untrained digit-span items, grammatical sentences, nongrammatical sentences, and match-to-sample items. A training procedure, in which 15 items from each class varied continually from trial to trial and from day to day, resulted in the percentage of correct responses to both training and probe items increasing to levels substantially above baseline. The results demonstrate the effectiveness of the training procedure in improving the generalized mnemonic performance of a Down's Syndrome child.     

Quasi-statistical inference in rating behavior I. Preliminary investigations

Bem and Allen (1974) have suggested that trait consistency-ratings can function as a moderator variable, with regard to the cross-situational validity of trait position-ratings. The present study attempts to consider the relationship between these two types of self-ratings. A model of “man the quasi-statistician” was proposed which yields the predictions that (a) consistency-ratings will vary positively with the polarization-estimate from position-ratings and (b) the extent of correlation will be a function of the degree of polarization associated with a given class of trait.In two experiments, position-ratings and consistency-ratings were obtained over a series of dimensions. The predictions were confirmed in both studies. In addition, Experiment II provided evidence for a correspondence between intuitive and formal estimates of central tendency polarization, although this was not the case for dispersion. The results were discussed as bearing on the model and as relating to the findings of Bem and Allen (1974).     

A comparison of self-directed and therapist-directed practice for fear reduction

Various amounts of self-directed and therapist-directed practice were evaluated in reducing fear of snakes. The conditions included an exclusively self-directed condition, a predominantly self-directed condition, a predominantly therapist-directed condition, and an exclusively therapist-directed condition. All treatments resulted in reduced fear on behavioral and self-report measures. The predominantly therapist-directed subjects showed more improvement than subjects in the exclusively self-directed and predominantly self-directed conditions, but not more improvement than subjects in the exclusively therapist-directed condition.     

Contribution of the speech musculature to apparent human EEG asymmetries prior to vocalization

Vocalizations are preceded by slow EEG waves over inferior frontal scalp regions, but some controversy exists as to whether these slow potentials are left-lateralized as a function of speech. In this study both speech and non-speech vocalizations were studied, under conditions of repetitive and variable production. Averaged responses over the speech musculature, including the temporalis, masseter, orbicularis oris, and mylohyoid muscles, as well as the eyes and tongue, were calculated simultaneously with scalp EEG averages. The responses of the temporalis and masseter muscles, as well as that of the tongue, were correlated with EEG sites at specific latencies prior to speech, suggesting that no part of the inferior frontal EEG record was free from myogenic confounds. In addition, all significant EEG differences between speech and non-speech conditions were subsequently eliminated by covariance analysis, using selected muscle channels as covariates. Previous reports of asymmetrical “speech potentials” in the EEG probably reflected a combination of several myogenic confounds.     

Effect of variable-interval punishment on the behavior of humans in variable-interval schedules of monetary reinforcement

One male and three female human subjects pressed a button for monetary reinforcement under a range of variable-interval schedules specifying different frequencies of reinforcement. On alternate days, responding was also punished (by subtraction of money) according to a variable-interval 170-second schedule. In the absence of punishment, the rate of responding was an increasing negatively accelerated function of reinforcement frequency, as predicted by Herrnstein's equation. The effect of the punishment schedule was to suppress responding under lower frequencies of reinforcement; responding under higher reinforcement frequencies was much less affected. This was reflected in an increase in the value of K_H (the constant expressing the reinforcement frequency corresponding to the half-maximal response rate), whereas there was no significant change in the value of R_max (the constant expressing the maximum response rate). Previous results had shown that variable-ratio punishment resulted in a change in the values of both constants (Bradshaw, Szabadi, and Bevan, 1977). The results of the present study were consistent with the concept that the suppressive effects of punishment on responding depend on the nature of the punishment schedule.     

The effect of question repetition within interviews on young children's eyewitness recall

This study investigated the influence of question repetition and question type (answerable, unanswerable, or opinion seeking) on children's recall. A total of 136 children (5-, 7-, and 9-year-olds) watched a live 15-min presentation. One week later, the children were asked 20 questions that were repeated an additional two times within the interview. Accuracy of children's responses to unanswerable questions declined with repetition. Children were more likely to change a response to an unanswerable question than to an answerable question. Overall, children maintained the same answers to only three-quarters of the repeated questions. The most common pattern of change was for children to change their answer the second time a question was asked and then to maintain that answer when questioned again. The high percentage of changed answers within a single interview has important implications for forensic interviewing.     

Are young children's drawings canonically biased?

In a between-subjects design, 4- to 6-year-olds were asked to draw from three-dimensional (3D) models, two-and-a-half-dimensional (212D) models with or without depth cues, or two-dimensional (2D) models of a familiar object (a saucepan) in noncanonical orientations (handle at the back or at the front). Results showed that canonical errors were produced mainly by the youngest children in the 3D models copying condition. A large proportion of errors did not, however, reflect biases toward the participants' "own" view of the object; rather, these errors reflected biases toward their "best" view of the object. Drawing from models having fewer than three dimensions resulted in a significant increase in view-specific productions in all children for the back orientation. When a more complex front orientation of the object was proposed, sensitivity to model type developed gradually with age. Results are discussed in terms of the flexibility of the mental model that mediates between children's perception of a model object and the depiction decisions.