Control of responding during stimuli that precede transitions in reinforcement frequency

Pigeons' responses were reinforced on a variant of a mixed variable-interval extinction schedule of reinforcement in which the transition to the higher reinforcement rate was signaled by a trace stimulus projected on the response key prior to the onset of the component correlated with food delivery. In the first of two experiments, the duration of the trace stimulus preceding the component correlated with food delivery was varied from 1.5 to 50.0 s and in the second experiment, the reinforcement frequency in the same component was varied from 10 to 60 reinforcers per hour. Pigeons pecked at the trace stimulus preceding the onset of the component correlated with food delivery even though responding was not reinforced in its presence and only one of the changes in reinforcement rate (i.e., from extinction to reinforcement) was signaled. The rate of pecking during the trace stimulus was a function of its duration but not of the reinforcement frequency in the following component. Higher rates generally occurred at the shorter trace-stimulus durations. Component responding following the offset of the trace stimulus was under discriminative control of the trace stimulus whether or not responding occurred in the presence of the trace stimulus.     

汉字刺激质量和频率在N400上的交互

采用事件相关电位,运用无启动的同一字判断（靶字延迟反应）范式,以大学生为被试探讨汉字刺激质量和频率是否具有交互作用。行为结果显示,刺激质量和频率在反应时上存在交互作用。脑电结果显示,重度模糊诱发了更大的N250和N400,且刺激质量和频率在N400上存在交互作用。结论是,汉字刺激质量和频率在反应时和N400上存在交互作用,表明在汉字识别中存在串级加工,支持IA模型。     

An evaluation of a visual–visual successive matching‐to‐sample procedure to establish equivalence classes in adults

Traditionally, behavior analysts have studied stimulus equivalence using a matching‐to‐sample (MTS) preparation. Although researchers have shown the utility of MTS to yield equivalence classes, the procedure requires several prerequisite skills for a learner to accurately respond. Previous research with humans and nonhumans has shown that relational responding can be produced via compound stimulus discrimination and successive matching‐to‐sample (S‐MTS). We conducted four experiments with college students to further evaluate the effectiveness of S‐MTS in the establishment of stimulus relations. S‐MTS trials consisted of the presentation of a single sample stimulus followed by one comparison in a fixed location on a computer screen. Depending upon the sample–comparison relation, participants touched (i.e., go) or did not touch (i.e., no‐go) the comparison stimulus. Following training of the baseline relations (AB/BC), we assessed the emergence of symmetry, transitivity, and equivalence performances (i.e., BA/CB and AC/CA). Results support the utility of the S‐MTS procedure as a possible alternative to traditional MTS. This study has direct implications for participants for whom traditional three‐array MTS procedures may be challenging.     

Verbal instructions targeting valence alter negative conditional stimulus evaluations (but do not affect reinstatement rates)

Negative conditional stimulus (CS) valence acquired during fear conditioning may enhance fear relapse and is difficult to remove as it extinguishes slowly and does not respond to the instruction that unconditional stimulus (US) presentations will cease. We examined whether instructions targeting CS valence would be more effective. In Experiment 1, an image of one person (CS+) was paired with an aversive US, while another (CS?) was presented alone. After acquisition, participants were given positive information about the CS+ poser and negative information about the CS? poser. Instructions reversed the pattern of differential CS valence present during acquisition and eliminated differential electrodermal responding. In Experiment 2, we compared positive and negative CS revaluation by providing positive/negative information about the CS+ and neutral information about CS?. After positive revaluation, differential valence was removed and differential electrodermal responding remained intact. After negative revaluation, differential valence was strengthened and differential electrodermal responding was eliminated. Unexpectedly, the instructions did not affect the reinstatement of differential electrodermal responding.     

Equivalence class formation as a function of preliminary training with pictorial stimuli

The present experiment investigated the effects of preliminary training with pictorial stimuli on the subsequent formation of three 5‐member equivalence classes (A?B?C?D?E) in 84 university students assigned to seven groups of 12. In the Abstract (ABS) group, all stimuli were abstract shapes. In the Picture (PIC) group, the C stimuli were pictures, and the remaining stimuli were the same abstract shapes as in the ABS group. For the remaining five groups, all stimuli were the same abstract shapes as in the ABS group. However, across groups, preliminary training involved either the establishment of conditional relations with simultaneous (SMTS) or delayed (DMTS) matching‐to‐sample with 0 s, 3 s, 6 s, or 9 s between the abstract C stimuli and the meaningful pictures. For the ABS and the PIC groups, 16.7% and 83.3% of participants formed classes, respectively. Preliminary training with SMTS and DMTS with 0 s, 3 s, and 6 s produced a linear increase in the likelihood of equivalence class formation, 41.7%, 50%, and 75%, respectively. Increasing the duration of delay further from 6 s to 9 s produced a substantial decline, 50%. This experiment extends knowledge about how including meaningful pictures enhances equivalence class formation.     

Factors that encourage generalization from extinction to test reduce resurgence of an extinguished operant response

Two experiments investigated methods that reduce the resurgence of an extinguished behavior (R1) that occurs when reinforcement for an alternative behavior (R2) is discontinued. In Experiment 1, R1 was first trained and then extinguished while R2 was reinforced during a 5‐ or 25‐session treatment phase. For half the rats, sessions in which R2 was reinforced alternated with sessions in which R2 was extinguished. Controls received the same number of treatment sessions, but R2 was never extinguished. When reinforcement for R2 was discontinued, R1 resurged in the controls. However, the alternating groups showed reduced resurgence, and the magnitude of the resurgences observed during their R2 extinction sessions decreased systematically over Phase 2. In Experiment 2, R1 was first reinforced with one outcome (O1). The rats then had two types of double‐alternating treatment sessions. In one type, R1 was extinguished and R2 produced O2. In the other, R1 was unavailable and R2 produced O3. R1 resurgence was weakened when O2, but not O3, was delivered freely during testing. Together, the results suggest that methods that encourage generalization between R1 extinction and resurgence testing weaken the resurgence effect. They are not consistent with an account of resurgence proposed by Shahan and Craig (2017).     

Evaluation of stimulus intensity fading on reduction of rapid eating in a child with autism

This study assessed the effects of a vibrating pager on reduction of rapid eating. The study also evaluated two strategies for fading the pager, by intensity and by frequency. The pager was successful in decreasing the pace of eating to an appropriate level and the pager prompt was successfully faded. Fading by frequency was ineffective in maintaining an appropriate pace of eating while intensity fading was successful.