Learning representations in a gated prefrontal cortex model of dynamic task switching

The prefrontal cortex is widely believed to play an important role in facilitating people's ability to switch performance between different tasks. We present a biologically‐based computational model of prefrontal cortex (PFC) that explains its role in task switching in terms of the greater flexibility conferred by activation‐based working memory representations in PFC, as compared with more slowly adapting weight‐based memory mechanisms. Specifically we show that PFC representations can be rapidly updated when a task switches via a dynamic gating mechanism based on a temporal‐differences reward‐prediction learning mechanism. Unlike prior models of this type, the present model develops all of its internal representations via learning mechanisms as shaped by the demands of continuous periodic task switching. This advance opens up a new domain of research into the interactions between working memory task demands and the representations that develop to meet them. Results on a version of the Wisconsin card sorting task are presented for the full model and a number of comparison networks that test the importance of various model features. Furthermore, we show that a lesioned model produces perseverative errors like those seen in frontal patients.     

The smoked plastic screen: An alternative to the one-way mirror

A double thickness, smoked plastic screen is presented as an alternative to the one-way mirror. Relative to the glass mirror, the use of the plastic screen provides a safe, nondistracting, durable, light weight, and inexpensive method for unobserved viewing without an appreciable loss in light transmission.     

Differential contributions of set-shifting and monitoring to dual-task interference

It is commonly argued that complex behaviour is regulated by a number of “executive functions”, which work to coordinate the operation of disparate cognitive systems in the service of an overall goal. However, the identity, roles, and interactions of specific putative executive functions remain contentious, even within widely accepted tests of executive function. The authors present two experiments that use dual-task interference to provide further support for multiple distinct executive functions and to establish the differential contributions of those functions in two relatively complex executive tasks—random generation and the Wisconsin Card Sorting Test. Results are interpreted in terms of process models of the complex executive tasks.     

Measuring the importance of information in judgment: Individual differences in weighting ability and effort

Measuring the importance of cues in social judgment has been a longstanding problem. Past research has shown individual differences in the impact of ability and study effort on judgments of student performance. This research examined the hypothesis that the individual differences are due to the weight given to the information as opposed to the perceived extremity of the values of the information. Subjects judged the performance of hypothetical students described by ability, study effort, and effort during an exam. Individual differences in the impact of the three types of information were obtained and were predictable from self-reports of the relative importance of information. Different values of weights were necessary to account for the differences in the impact of information, although there were also differences in the perceived extremity of the information. The theoretical and applied significance of distinguishing the weight given to information in judgment from its subjective value are discussed. On the basis of a new review of the literature, as well as the present results, it is concluded that self-reports of the relative importance of information are predictive of individual differences in information use in judgment, but that they may reflect the total impact of information rather than only the weight.     

Deficits in set-shifting ability in nonclinical compulsive checkers

Recent studies suggest deficits in set-shifting ability in patients with obsessive-compulsive disorder (OCD) as measured by tasks such as the Wisconsin Card Sorting Test (WCST; Berg, 1948). The present study examined the extent to which these deficits were demonstrated by nonclinical subjects selected on the basis of their checking scores on the Maudsley Obsessional-Compulsive Inventory. A multivariate analysis revealed that frequent checkers performed significantly worse on the WCST than noncheckers, making more total errors and more perseverative errors and requiring more time to complete the test. A follow-up analysis on a subset of the original sample found similar performance deficits in checkers. While the poorer performance of checkers could be statistically accounted for by anxiety during the first administration of the WCST, anxiety could not explain the relationship between checking status and WCST performance at follow-up. Therefore, there does appear to be some relationship between checking status and WCST performance beyond what can be explained by affective variables.     

Father identification,achievement, and occupational behavior of rural youth: 10-year follow-up

Males from rural economically deprived school districts, who had previously been surveyed as high school seniors, again 1 year after graduation, and again 5 years after graduation, were surveyed a fourth and final time 10 years after high school graduation concerning their occupational status and aspirations, their marital status, their spouses' educational and occupational achievements, the importance of life roles, and their occupational and personal satisfactions. In the original study the participants had been divided into two groups, low-identification males (LIM) and high-identification males (HIM) based on independent evaluators' judgments of the adequacy of their fathers as identification models. Each group's responses to the survey were compared. The results indicate that there were no statistically significant differences between the two groups on the variables of optimism about the future, spouses' occupational achievements, role importance, occupational satisfaction, and personal satisfaction. There were statistically significant differences on the variables of occupational status, occupational aspirations, educational achievements, educational plans, marital status, and spouses' educational achievements. The results are discussed in the context of the three previous surveys. Over the 10-year period the occupational and educational achievements and aspirations have been significantly higher for the HIM group than for the LIM group. Equally consistent is the finding that over the 10-year period there has been no differences between the two groups in satisfaction with status.     

Depression and the generation of complex hypotheses in the judgment of contingency

This experiment tests the hypothesis that relative to nondepressed college students, depressed college students will underestimate the potential amount of control they can exert over an environmental outcome when they must generate a complex hypothesis in order to exert control, but not when the complex hypothesis is generated for them. Following the method of Alloy and Abramson (1979b), depressed and nondepressed students' judgments of response-outcome contingency were assessed in either a ‘self-generated’ or an ‘experimenter-generated’ condition. In the ‘self-generated’ condition, subjects generated and tested potential hypotheses for controlling the outcome themselves. In the ‘experimenter-generated’ condition, the experimenter generated a small set of potential hypotheses to be tested by the subject. Relative to nondepressed students, depressed students were less likely to perform the correct controlling response, received fewer rewards, and judged that they exerted less control over the outcome in the ‘self-generated’ condition. These results fail to support the ‘associative’ deficit of the learned helplessness theory of depression, but are consistent with the ‘motivational’ deficit of helplessness theory.     

Growth functions for rapid remembering

Children between ages 9 and 13 were tested for recognizing and remembering words from 6- and 12-word lists. Opportunities for using deliberate mnemonics were severely restricted. Developmental functions showed different growth patterns for remembering the items in a short list than for remembering order, and different patterns for storing items from a long list than for retrieving them. However, none of these functions was parallel to the growth function of rapid word recognition. This absence of parallel growth contradicted a hypothesis that memory develops when item recognition develops. The data suggested, instead, that modest but reliable gains in rapid processes of storage and retrieval contribute to memory development during middle childhood.     

Necessary versus sufficient causal schemata: Attributions for achievement in difficult and easy tasks

Previous research on Kelley's schemata for multiple sufficient and multiple necessary causes has failed to examine the hypothesis that a schema influences both predictions of an event and attributions of its causes. This research examined the effects of the difficulty of a hypothetical exam on predictions of exam grades, and on attributions of ability and effort. Exam difficulty influenced both the pattern of judgments of grades and reported beliefs in multiple necessary versus multiple sufficient causes. Contrary to the predictions of the schema theory, exam difficulty had little influence on the pattern of attributions of ability and effort. Kelley's concept of a causal schema is reinterpreted in terms of current views of human judgment, and the possible implications of the data for the interpretations of a causal schema are examined. The results question the assumption that attributions are based on beliefs about how causes combine to determine an effect, and suggest further research on the relationship between predictions and attributions.     

Dissociative effects of flooding on a multivariate assessment of fear reduction and on jump-up avoidance extinction

Two experiments examined the effectiveness of three different amounts of flooding on hastening extinction of a jump-up avoidance response and on reducing fear as assessed by the multivariate fear assessment techniques of D. P. Corriveau and N. F. Smith (Journal of Experimental Psychology: General, 1978, 107, 145–158). In Experiment 1, a 40-min flooding treatment significantly hastened jump-up avoidance extinction, 10 min of flooding had a marginal effect, and 5 min had no effect. In Experiment 2, flooding treatments of 5, 10, and 40 min duration were all effective in reducing fear of the grid floor as indexed by seven of our nine dependent measures, including approach latency, safety test latency, and amount of time spent on the grids. Flooded subjects that were dumped onto the grid floor once at the start of the fear observation phase were found to show somewhat more fear reduction than were flooded subjects that were simply placed on the ledge at the outset of the fear observation phase and never dumped. These results, i.e., less flooding is required to reduce fear than to hasten avoidance extinction, are contrasted with those of previous experiments indicating that more flooding may be required to reduce fear than to hasten shuttlebox avoidance extinction. Such differences are discussed in the context of SSDR theory.