The role of the nucleus accumbens in knowing when to respond

While knowing what to expect is important, it is equally important to know when to expect it and to respond accordingly. This is apparent even in simple Pavlovian training situations in which animals learn to respond more strongly closer to reward delivery. Here we report that the nucleus accumbens core, an area well-positioned to represent information about the timing of impending rewards, plays a critical role in this timing function.     

n-back任务下视觉工作记忆负荷研究

实验采用n-back范式,考察了视觉工作记忆负荷与反应时、辨别力和主观评价的关系,以及空间位置记忆负荷与图形记忆负荷的差异。结果发现,随着记忆负荷的增大,反应时延长,辨别力降低,主观负荷提高。视觉图形记忆任务的负荷水平高于视觉空间位置记忆任务的负荷水平;同时也为视觉图形记忆和视觉空间记忆具有不同的加工过程提供了证据。     

Resurgence is greater following a return to the training context than remaining in the extinction context

The present study examined whether resurgence of a previously reinforced target response upon removing alternative reinforcement would be greater when (1) returning to the original training context (ABA context changes) versus (2) remaining in the analogue treatment context in which the alternative response was differentially reinforced (ABB context changes). Experiment 1 arranged reinforcement of button pressing with points exchangeable for money in university students. Experiment 2 arranged reinforcement of lever pressing with food for rats. Experiment 3 arranged reinforcement of responses to a touchscreen with small bites of food with children diagnosed with ASD. Overall, resurgence of target responding tended to be greater when returning to the original training context (A) than when remaining in the analogue treatment context (B). These findings suggest context changes with differential reinforcement treatments could exacerbate the recurrence of problem behavior resulting from reductions in treatment integrity through failure to reinforce appropriate behavior.     

Behavioral and neural correlates of memory selection and interference resolution during a digit working memory task

Neuroimaging studies have shown the involvement of prefrontal and posterior parietal cortexes in regulating information processing. We conducted behavioral and fMRI experiments to investigate the relationship between memory selection and proactive interference (PI), using a delayed recognition task with a selection cue presented during the delay indicating which two of the four studied digits were relevant to the present test. PI was indexed by the response time differences between rejecting probes matching and not matching the no longer relevant digits. By varying the delay intervals, we found that the effect of PI did not diminish, even for cases in which the postcue interval was extended to 9 sec, but was stronger when the precue interval was lengthened to 5 sec. By examining the correlation between PI index and neural correlates of memory selection, we found that stronger PI is predicted by lower selection-related activity in the left inferior parietal lobe, the precuneus, and the dorsal middle frontal gyrus. Our results suggest that activity in the prefrontal-parietal network may contribute to one’s ability to focus on the task-relevant information and may proactively reduce PI in working memory.     

Distance constancy: Functional relationships between apparent distance and physical distance

Summary Distance constancy was clearly defined with Thouless and Brunswik indexes by examining its previous definitions. The typical functions expressing the relationships between apparent distance and physical distance were derived from; 1. much available data obtained by many researchers, 2. Thouless and Brunswik indexes (formulas), 3. Luneburg's theory. These derived functions were classified into type I, II and III according to their psychological significance. The validity of the classification was verified by experiments showing that the functions of type III were available in poorly articulated spaces with a long viewing distance, that is, on a housetop and a road, with the method of equal appearing intervals. Moreover, the relationships between distance constancy and personal constants in Luneburg's theory were clarified.

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Zusammenfassung In der vorliegenden Arbeit wird die Entfernungskonstanz nach Überprüfung ihrer früheren Definitionen mit Thouless' und Brunswiks Indexen genau definiert. Die typischen Funktionen, die die Beziehungen zwischen scheinbarer Entfernung und physikalischer Entfernung zeigen, werden abgeleitet aus 1. den verfügbaren Forschungsergebnissen zahlreicher Gelehrter, 2. Thouless' und Brunswiks Indexen (Formeln), 3. Luneburgs Theorie. Diese abgeleiteten Funktionen werden ihrer psychologischen Bedeutung entsprechend in Typus I, II und III eingeteilt. Die Gültigkeit dieser Klassifikation wurde durch Experimente verifiziert, die mit der Anwendung der Methode von gleich erscheinenden Abständen zeigen, daß die Funktionen vom Typus III in ungenügend artikulierten Räumen mit einer langen Beobachtungsentfernung, d.h. auf einem Dach und einem Weg, gültig sind. Außerdem werden die Beziehungen zwischen Entfernungskonstanz und Personalkonstante in Luneburgs Theorie festgestellt.

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I wish to express my thanks to Professor Yoshiharu Akishige for his guidance in this field of work, and Dr. Katsumi Ishii, the retired professor of Kyushu University, for his invaluable suggestions, especially for constant guidance in the problems of Luneburg's theory. Thanks are also due to Assistant Professor Masao Hashiguchi of Kagoshima University for his valuable advice and generous help concerning the mathematical problems. I am also indebted to the students of our department for their help in carrying out the experiments.     

Early extinction effects following intermittent reinforcement: Little evidence of extinction bursts

The occurrence of extinction bursts—transient increases in response rate in excess of those observed in baseline during the period immediately following discontinuation of reinforcement of a response—was examined. In Experiment 1, key pecking of pigeons was reinforced according to a multiple schedule in which a variable-ratio schedule alternated with an interval schedule in which the reinforcers were yoked to the preceding variable-ratio component. In Experiments 2 and 3, rats were screened such that the lever-press response rates of different rats maintained by variable-interval schedules were either relatively high or relatively low. Following these baseline conditions, in Experiments 1 and 2 responding was extinguished by eliminating the food reinforcer and in Experiment 3 by removing the response–reinforcer dependency. Responses immediately following extinction implementation were examined. Response increases relative to baseline during the first 20 min of a 324.75-min extinction session (Experiment 1) or during the first 30-min extinction session (Experiments 2 and 3) were rare and unsystematic. The results (a) reinforce earlier meta-analyses concluding that extinction bursts may be a less ubiquitous early effect of extinction than has been suggested and (b) invite further experimentation to establish their generality as a function of preceding reinforcement conditions.     

A conjunctive feature similarity effect for visual search

Traditional models of visual search assume interitem similarity effects arise from within each feature dimension independently of other dimensions. In the present study, we examine whether distractor-distractor effects also depend on feature conjunctions (i.e., whether feature conjunctions form a separate “feature” dimension that influences interitem similarity). Spatial frequency and orientation feature dimensions were used to generate distractors. In the bound condition, the number of distractors sharing the same conjunction of features was higher than that in the unbound condition, but the sharing of features within frequency and orientation dimensions was the same across conditions. The results showed that the target was found more efficiently in the bound than in the unbound condition, indicating that distractor-distractor similarity is also influenced by conjunctive representations.     

The Automatic Activation of Retributive Motive When Determining Punishment

This study sought to test the hypothesis that an individual’s retributive motive is activated automatically when he or she is presented with an opportunity to determine appropriate punishment. Fifty-one undergraduate students were subjected to one of two conditions: one in which an video clip of a brutal crime was presented (crime video condition) and another in which a sports documentary video clip was presented (sports video condition). Participants were asked to complete the Implicit Association Test before and after being presented with the video. It was predicted that the activation of retributive motive would strengthen the association with a balanced combination of these factors as compared to the association with an unbalanced combination of factors and increase the IAT effect accordingly. The IAT effect increased in the crime video condition but did not change in the sports video condition. This result supported the hypothesis, indicating that decision making regarding punishment is carried out automatically and outside of conscious awareness, as the IAT reflects automatic cognitive processes such as implicit attitudes.     

Examining effects of training duration on humans' resurgence and variability using a novel touchscreen procedure

Resurgence occurs when a previously reinforced and then extinguished target response increases due to reducing/eliminating an alternative source of reinforcement or punishing an alternative response. We evaluated whether duration of reinforcement history for a target response (1) affects the degree to which resurgence is observed in humans and (2) produces different gradients of response generalization around target responding during extinction testing. We arranged a novel touchscreen interface in which university students could swipe a 3D soccer ball to spin any direction. In Phase 1, the first direction swiped became the target and produced points exchangeable for money for 3 or 1 min across 2 groups. The first swipe was recorded but had no programmed consequence in a third group. In Phase 2, swipes 180-degrees from the target resulted in points for 3 min in all groups. Point deliveries ceased for 2 min to test for resurgence in Phase 3. Target responses resurged during testing to a relatively greater extent with longer Phase-1 training but gradients of response generalization did not differ among groups. These findings extend prior research on the role of training duration on resurgence. We discuss methodological and conceptual issues surrounding the assessment of response generalization in resurgence.