Autoshaping with common and distinctive stimulus elements, compact and dispersed arrays

Four groups of pigeons were trained with a standard autoshaping procedure in which a brief fixed-duration interval always followed by a grain delivery alternated with a longer variable-duration interval never associated with grain delivery. One of two stimuli was always presented during each interval. One of them contained three black dots and a black star on a green background; the other contained four black dots on a green background. The four elements of each stimulus were arranged in a more compact array for two groups and in a more dispersed array for the other two groups. Which of the two stimuli preceded grain delivery was counterbalanced within each pair of groups. The speed of occurrence of the first autoshaped peck was not affected by whether the stimulus containing the distinctive star element preceded grain delivery, but autoshaping was faster when the stimulus arrays were compact than when they were dispersed. During 560 response-independent training trials that followed the first autoshaped peck, this pattern reversed; both discriminative control over responding and the relative frequency of pecking the stimulus that preceded grain delivery were greater for the two groups where this stimulus contained the discriminative element than for the two groups where it contained only common elements. During subsequent testing with stimuli containing only a single element each, the distinctive feature was responded to proportionately more often by the two groups for which it had been an element of the stimulus preceding grain delivery than by the two groups for which it had been an element of the stimulus complex that never was associated with grain delivery. These data add further support to the hypothesis that the initial occurrence of autoshaped responding and its subsequent maintenance are not affected by the same variables. They also suggest that automaintenance is as sensitive as response-dependent training to the presence or absence of a distinctive stimulus element among several common elements and that this sensitivity appears to be independent of the specific method used for presenting the stimuli during automaintenance.     

Choice of timeout during response-independent food schedules

Rats' lever pressing terminated visual or auditory stimuli associated with fixed-time or variable-time schedules of food delivery and produced a timeout period during which food delivery could not occur. Lever pressing during a timeout period reinstated the food-associated stimuli and again permitted food delivery according to the fixed-time or variable-time schedules. The mean interfood interval ranged from 1 minute to 16 minutes (variable-time schedules) or 32 minutes (fixed-time schedules); the timer controlling schedule intervals did not stop during timeout periods. The percentage of session time spent in timeout increased when the mean interfood intervals were lengthened and decreased when the mean interfood intervals were shortened. Timeouts were initiated most frequently about half way between successive food deliveries (fixed-time schedules) or after 15 seconds or more had lapsed since the last food delivery (variable-time schedules). Elimination of food delivery increased the percentage of session time spent in timeout, and elimination of the timeout contingency decreased lever press rates. When timeout was produced only when the lever was held in the depressed position, little time was spent in timeout. The main determinants of timeout initiation and termination appeared to be the rate of food delivery, freedom of movement during timeout, and the stimulus change associated with initiation and termination of timeout.     

Effects of response-produced stimuli upon conditional discrimination performance

In zero-delay matching procedures the performance of three groups of pigeons was examined when exteroceptive stimuli, response-produced stimuli associated with the completion of either of two fixed ratios, or a compound of exteroceptive and response-produced stimuli were available as samples. Exteroceptive samples were found to control a higher level of matching accuracy than response-produced samples, while compound samples controlled a higher level of accuracy than did exteroceptive samples alone. When all subjects were placed on a transfer procedure, during which the previously used red and green samples were replaced by horizontal and vertical lines, the availability of sample-specific fixed-ratios facilitated acquisition of the task.     

Individual differences in dopamine D<Subscript>2</Subscript> receptor availability correlate with reward valuation

Reward valuation, which underlies all value-based decision-making, has been associated with dopamine function in many studies of nonhuman animals, but there is relatively less direct evidence for an association in humans. Here, we measured dopamine D₂ receptor (DRD2) availability in vivo in humans to examine relations between individual differences in dopamine receptor availability and neural activity associated with a measure of reward valuation, expected value (i.e., the product of reward magnitude and the probability of obtaining the reward). Fourteen healthy adult subjects underwent PET with [¹⁸F]fallypride, a radiotracer with strong affinity for DRD2, and fMRI (on a separate day) while performing a reward valuation task. [¹⁸F]fallypride binding potential, reflecting DRD2 availability, in the midbrain correlated positively with neural activity associated with expected value, specifically in the left ventral striatum/caudate. The present results provide in vivo evidence from humans showing midbrain dopamine characteristics are associated with reward valuation.     

Community Psychology at the Crossroads: Prospects for Interdisciplinary Research

Effective engagement in interdisciplinary work is critical if community psychology is to achieve its promise as a field of ecological inquiry and social action. The purpose of this paper and special issue is to help make the benefits of interdisciplinary community research clearer and to identify and begin to address its challenges. Although some areas of psychology (e.g., biological, cognitive and health) have made substantial interdisciplinary strides in recent decades, progress in community psychology (and related areas) is more modest. In this article we explore the prospects for expanding and improving interdisciplinary community research. Challenges include designs, measures, and analytical frameworks that integrate multiple levels of analysis from individuals through families, organizations, and communities to policy jurisdictions, and the complexities involved in simultaneously bringing together multiple disciplinary collaborators and community partners. Challenges to interdisciplinary collaboration common to all disciplines include the disciplinary nature of academic culture and reward structures, limited funding for interdisciplinary work and uncertainties related to professional identity and marketability. Overcoming these challenges requires a synergy among facilitative factors at the levels of the interdisciplinary project team (e.g., the framing question; embedded relationships; leadership), the investigators (e.g., commitment to new learning; time to invest), and the external context (e.g., physical, administrative, economic and intellectual resources and support for interdisciplinary work). We conclude by identifying several exemplars of effective interdisciplinary collaborations and concrete steps our field can take to enhance our development as a vibrant community-based, multilevel discipline increasingly devoted to interdisciplinary inquiry and action.     

Democratic School Climate and Sense of Community in School: A Multilevel Analysis

This study examines individual- and school-level predictors of sense of community in school among adolescents. Hierarchical linear modeling was used to examine the relationships between individual (demographics, control and monitoring by parents, and perception of democratic school climate), class, and school characteristics (mean democratic school climate, demographics, activities, school size, public/private governance of the school, and facilities) and students' sense of community in the school. Data were analyzed using a three-level model based on 4,092 10- to 18-year-old students nested within 248 classes (across three grade levels: 6th, 8th, and 10th grade level, where the median age was 11, 13, and 15, respectively) in 134 schools in the Veneto region of northeast Italy. Individual and contextual measures of the perception of a democratic school climate, modeled at the individual, class, and school levels simultaneously, were each significant predictor of school sense of community. More parental monitoring and less parental control were also predictive at the individual level. School-level SES predicted between school variation in sense of community, controlling for individual student SES and other student and school-level predictors. School size, facilities (physical spaces resources), level of interaction of the school with the community, public, or private governance, and number of extracurricular activities offered were all nonsignificant. The study demonstrates significant variation in school sense of community at the student, class, and school levels and the important role played by democratic school practices, such as student participation in making rules and organizing events, freedom of expression, and the perceived fairness of rules and teachers, in determining this variable.     

The comrade on the crossroads of scholarship and struggle: Troubling the exile of Frantz Fanon from social and political psychology

This article traces the presence and absence of Frantz Fanon in the field of social and political psychology. Our work is guided by an assemblage of methods— a critical analysis of mainstream scholarship, a collective interrogation with a transnational gathering of colleagues and friends, and a deep reading of Fanon's texts on struggle, internalized oppression, violence and a new humanism. Through this, our paper is a call for radical disciplinary reflection on why Fanon has been ruthlessly exiled from social/political psychology, the potential his writings hold for courses, scholarship, and struggle, and how we might more boldly theorize, as he did, from within the fire of struggles for justice and liberation.