Culture and beliefs about time: comparisons among black Americans, black Africans, and white Americans

The authors investigated the extent to which racial factors, cultural factors, or both influence a person's beliefs about physical time, personal time, and experienced and remembered duration. A total of 750 Black American, Black African, and White American students responded to a questionnaire on these beliefs about time. Factor analysis was used to compare belief structures. Pairwise comparisons, performed separately for each statement, tested the direction and strength of the reported beliefs. The groups showed many similarities, but they also showed some differences. All 3 groups differed in beliefs about physical and personal time, but they did not differ in beliefs about duration experiences. This evidence does not support simplistic views of racial or cultural influences. Culture may differentially influence beliefs about physical time and personal time. Beliefs about duration experiences may represent an ethnic factor that transcends cultures.     

Gamma-range oscillations in backward-masking functions and their putative neural correlates

Backward-masking functions have been hitherto categorized into two types, commonly named Type A and Type B. The analysis of a model of Retino-Cortical Dynamics produces the prediction that spatially localized stimuli should reveal an oscillatory metacontrast function. The predicted new type of metacontrast masking function was investigated in a psychophysical experiment. The results show oscillatory metacontrast functions with significant power in the gamma range (30-70 Hz). A marked decrease in the oscillations is observed when the spatial extent of the stimuli is increased. The theoretical basis of the study relates the oscillations found in the metacontrast function to gamma-range oscillations observed in scalp and intracerebral recordings. The qualitative agreement between the model and data provides support for this putative relationship.     

A diathesis-stress conceptualization of expressed emotion and clinical outcome

A sizeable body of research has demonstrated that expressed emotion (EE) predicts clinical relapse in a number of distinct psychiatric disorders. These findings have provided the impetus for the development of interventions that attempt to reduce patients' relapse rates by modifying aspects of the family environment believed to be associated with high levels of EE. Despite the efficacy of these treatments, however, we know little about how EE develops in relatives of psychiatric patients or about the mechanisms through which high EE leads to relapse. Moreover, there is not a coherent theory that attempts to integrate findings concerning the impact of high EE on relapse in different disorders. The purpose of this article is to elucidate a diathesis-stress conceptualization of EE to explain both the development and manifestation of high EE in relatives of disordered patients and the impact of high EE on the course of patients' disorders. In this context, we use a diathesis-stress perspective to examine why EE predicts symptom relapse and poor clinical outcome in schizophrenia, depressive disorders, and borderline personality disorder. We conclude by discussing treatment implications of the diathesis-stress perspective and by outlining what we believe are fruitful directions for future research.     

Evaluation of a Web-based introductory psychology course: II. Contingency management to increase use of on-line study aids

In a Web-based general psychology course, students were observed to postpone use of on-line study aids until 2 days prior to examinations, thus negating any influence of advance organizers (Taraban, Maki, & Rynearson, 1999). We attempted to modify this behavior by providing course credit in the form of short quizzes as rewards for using on-line study aids to preview each chapter. Some students received quizzes after previewing frequently asked questions (FAQ); other students received quizzes after previewing chapter outlines. Students who received quizzes for previewing FAQ pages accessed those pages more frequently than did students who received quizzes for previewing outline pages. Increased access to FAQs was associated with higher scores on FAQ-related midterm examination questions. However, the advantage on examination items was not apparent on a cumulative final examination. Navigational structures and reward values need to be considered when one is managing contingencies in Web courses.     

Tell me, what did you see? The stimulus on computers

Most psychology experiments start with a stimulus, and, for an increasing number of studies, the stimulus is presented on a computer monitor. Usually, that monitor is a CRT, although other technologies are becoming available. The monitor is a sampling device; the sampling occurs in four dimensions: spatial, temporal, luminance, and chromatic. This paper reviews some of the important issues in each of these sampling dimensions and gives some recommendations for how to use the monitor effectively to present the stimulus. In general, the position is taken that to understand what the stimulus actually is requires a clear specification of the physical properties of the stimulus, since the actual experience of the stimulus is determined both by the physical variables and by the psychophysical variables of how the stimulus is handled by our sensory systems.     

Effects of methylphenidate on sensitivity to reinforcement in children diagnosed with attention deficit hyperactivity disorder: an application of the matching law

The behavior of children diagnosed with attention deficit hyperactivity disorder (ADHD) has been hypothesized to be the result of decreased sensitivity to consequences compared to typical children. The present study examined sensitivity to reinforcement in 2 boys diagnosed with ADHD using the matching law to provide more precise and quantitative measurement of this construct. This experiment also evaluated the effects of methylphenidate (MPH) on sensitivity to reinforcement of children with ADHD. Subjects completed math problems to earn tokens under four different variable-interval (VI) schedules of reinforcement presented in random order under both medicated and nonmedicated conditions. Results showed that, in the medicated condition, the matching functions for both subjects resulted in higher asymptotic values, indicating an overall elevation of behavior rate under these conditions. The variance accounted for by the matching law was also higher under the medicated conditions, suggesting that their behavior more closely tracked the changing rates of reinforcement while taking MPH compared to placebo. Under medicated conditions, the reinforcing efficacy of response-contingent tokens decreased. Results are discussed with respect to quantifying behavioral changes and the extent to which the drug interacts with prevailing contingencies (i.e., schedule values) to influence behavioral variability.     

Repeated assessment of the Tower of Hanoi test: reliability and age effects

The purpose of this research was to analyze the effects of repeating an executive function test. Three versions of the Tower of Hanoi (TOH) test were repeated three times each, with test-retest intervals of 2 months. Two groups of children participated in the research (7.7 and 11.6 years, n = 22 and n = 28). Repeating the assessment improved the performance and decreased the total performance time in both of the groups. The older participants improved their performance faster than the younger ones. The reliability of all the scores, besides the error scores, seemed to be satisfactory after the first few assessments. The stability of the scores was maintained through all the assessments. The planning time did not explain the variations of the achieved score. The reasons for the initially low reliabilities are discussed, and modifications for the test administration and scoring are suggested.     

Frontal-Lobe Involvement in Spatial Memory: Evidence from PET,fMRI, and Lesion Studies

Many studies have identified the prefrontal cortex as the brain area that is critical for spatial memory, both in humans and in other primates. Other studies, however, have failed to establish this relation. Therefore, the aim of this paper was to review the literature regarding the role of the human prefrontal lobe in spatial memory. This was done by examining the evidence obtained from neuropsychological patients and from studies using brain-imaging techniques (PET and fMRI). Evidence supporting the notion that the prefrontal cortex is extensively involved in spatial working memory was found. The majority of these studies, however, suggests that frontal-lobe involvement is not related to the type of material that is being processed (e.g., spatial vs. nonspatial), but to process-specific functions, such as encoding and retrieval. Theoretically, these functions could be linked to the central executive within Baddeley's working-memory model, or to recent theories that emphasize the various processes that play a role in working memory. Also, methodological issues were discussed. Further research is needed to enhance our understanding of the precise interaction of domain-specific and general processes.