女性生理周期对条件性恐惧习得和消退的影响

动物研究显示, 雌激素调节条件性恐惧习得和消退, 但是, 人类的性激素对条件性恐惧习得和消退的影响还不太清楚。因此, 本研究以大学生为研究对象, 考察女性不同生理周期对条件性情境恐惧的习得和消退的影响。20名经前期和20名经期女被试暴露于3种情境下：无厌恶刺激情境(N)、可预测情境(P)和不可预测情境(U), 预测此3种情境下是否出现厌恶刺激。以在线索条件下和无线索条件下对厌恶刺激的主观预期值为因变量。研究结果显示:在习得阶段, 经期女性在P情境下的条件性线索恐惧的主观预期值高于经前期女性; 经前期女性在3种情境下的条件性情境恐惧的主观预期值都高于经期女性, 但只在N情境和P情境, 与经期女性相比, 经前期女性对厌恶刺激的主观预期值存在显著差异。在消退阶段, 与经期女性相比, 经前期女性在3种情境下的条件性情境恐惧的主观预期值更高, 且经前期女性对厌恶刺激的主观预期值在N情境和P情境显著高于经期女性。该结果显示, 经前期女性对条件性情境恐惧易习得难消退, 表明此生理阶段的性激素影响大脑的情绪调节功能, 从而影响条件性情境恐惧。     

How do reinforcers affect choice? Preference pulses after responses and reinforcers

In concurrent schedules, reinforcers are often followed by a brief period of heightened preference for the just‐productive alternative. Such ‘preference pulses’ may reflect local effects of reinforcers on choice. However, similar pulses may occur after nonreinforced responses, suggesting that pulses after reinforcers are partly unrelated to reinforcer effects. McLean, Grace, Pitts, and Hughes (2014) recommended subtracting preference pulses after responses from preference pulses after reinforcers, to construct residual pulses that represent only reinforcer effects. Thus, a reanalysis of existing choice data is necessary to determine whether changes in choice after reinforcers in previous experiments were actually related to reinforcers. In the present paper, we reanalyzed data from choice experiments in which reinforcers served different functions. We compared local choice, mean visit length, and visit‐length distributions after reinforcers and after nonreinforced responses. Our reanalysis demonstrated the utility of McLean et al.'s preference‐pulse correction for determining the effects of reinforcers on choice. However, visit analyses revealed that residual pulses may not accurately represent reinforcer effects, and reinforcer effects were clearer in visit analyses than in local‐choice analyses. The best way to determine the effects of reinforcers on choice may be to conduct visit analyses in addition to local‐choice analyses.     

Stimuli previously associated with reinforcement mitigate resurgence

Resurgence refers to the recurrence of an extinguished target behavior following subsequent suspension of alternative reinforcement. Delivery of reinforcers during extinction of alternative behavior has been shown to mitigate resurgence. The present experiment aimed to determine whether delivering stimuli associated with reinforcers during resurgence testing similarly mitigates resurgence. Three groups of rats pressed target levers for food according to variable‐interval 15‐s schedules during Phase 1. In Phase 2, lever pressing was extinguished, and an alternative nose‐poke response produced alternative reinforcement according to a variable‐interval 15‐s schedule. Food reinforcement was always associated with illumination of the food aperture and an audible click from the pellet dispenser during Phases 1 and 2. Phase 3 treatments differed between groups. For one group, nose poking continued to produce food and food‐correlated stimuli. Both of these consequences were suspended for a second group. Finally, nose poking produced food‐correlated stimuli but not food for a third group. Target‐lever pressing resurged in the group that received no consequences and in the group that received only food‐correlated stimuli for nose poking. Resurgence, however, was smaller for the group that received food‐correlated stimuli than for the group that received no consequences for nose poking. Target‐lever pressing did not increase between phases in the group that continued to receive food and associated stimuli. Thus, delivery of stimuli associated with food reinforcement after suspension of food reduced but did not eliminate resurgence of extinguished lever pressing. These findings contribute to potential methodologies for preventing relapse of extinguished problem behavior in clinical settings.     

Disruption of responding maintained by conditioned reinforcement: alterations in response-conditioned-reinforcer relations

An observing procedure was used to investigate the effects of alterations in response-conditioned-reinforcer relations on observing. Pigeons responded to produce schedule-correlated stimuli paired with the availability of food or extinction. The contingency between observing responses and conditioned reinforcement was altered in three experiments. In Experiment 1, after a contingency was established in baseline between the observing response and conditioned reinforcement, it was removed and the schedule-correlated stimuli were presented independently of responding according to a variable-time schedule. The variable-time schedule was constructed such that the rate of stimulus presentations was yoked from baseline. The removal of the observing contingency reliably reduced rates of observing. In Experiment 2, resetting delays to conditioned reinforcement were imposed between observing responses and the schedule-correlated stimuli they produced. Delay values of 0, 0.5, 1, 5, and 10 s were examined. Rates of observing varied inversely as a function of delay value. In Experiment 3, signaled and unsignaled resetting delays between observing responses and schedule-correlated stimuli were compared. Baseline rates of observing were decreased less by signaled delays than by unsignaled delays. Disruptions in response-conditioned-reinforcer relations produce similar behavioral effects to those found with primary reinforcement.     

Effects of reinforcer consumption and magnitude on response rates during noncontingent reinforcement

Results of previous research on the effects of noncontingent reinforcement (NCR) have been inconsistent when magnitude of reinforcement was manipulated. We attempted to clarify the influence of NCR magnitude by including additional controls. In Study 1, we examined the effects of reinforcer consumption time by comparing the same magnitude of NCR when session time was and was not corrected to account for reinforcer consumption. Lower response rates were observed when session time was not corrected, indicating that reinforcer consumption can suppress response rates. In Study 2, we first selected varying reinforcer magnitudes (small, medium, and large) on the basis of corrected response rates observed during a contingent reinforcement condition and then compared the effects of these magnitudes during NCR. One participant exhibited lower response rates when large-magnitude reinforcers were delivered; the other ceased responding altogether even when small-magnitude reinforcers were delivered. We also compared the effects of the same NCR magnitude (medium) during 10-min and 30-min sessions. Lower response rates were observed during 30-min sessions, indicating that the number of reinforcers consumed across a session can have the same effect as the number consumed per reinforcer delivery. These findings indicate that, even when response rate is corrected to account for reinforcer consumption, larger magnitudes of NCR (defined on either a per-delivery or per-session basis) result in lower response rates than do smaller magnitudes.     

Using simultaneous presentation to increase vegetable consumption in a mildly selective child with autism

A multiple baseline design was used to evaluate the effects of adding condiments on the consumption of previously rejected foods (vegetables). Adding condiments produced increased food acceptance across three food items. Data are discussed in relation to conditioned food preferences and establishing operations.     

Response-restriction analysis: II. Alteration of activity preferences

We used response-restriction (RR) assessments to identify the preferences of 7 individuals with mental retardation for a variety of vocational and leisure activities. We subsequently increased their engagement in nonpreferred activities using several procedures: response restriction per se versus a Premack-type contingency (Study 1), supplemental reinforcement for engagement in target activities (Study 2), and noncontingent pairing of reinforcers with nonpreferred activities (Study 3). Results indicated that preferences are not immutable and can be altered through a variety of relatively benign interventions and that the results of RR assessments may be helpful in determining which types of procedures may be most effective on an individual basis.     

Resistance to change of forgetting functions and response rates

This experiment examined the effects of reinforcement probability on resistance to change of remembering and response rate. Pigeons responded on a two-component multiple schedule in which completion of a variable-interval 20-s schedule produced delayed matching-to-sample trials in both components. Each session included four delays (0.1 s, 2 s, 4 s, and 8 s) between sample termination and presentation of comparison stimuli in both components. The two components differed in the probability of reinforcement arranged for correct matches (i.e., rich, p = .9; lean, p = .1). Response rates during the variable-interval portion of the procedure were higher in the rich component during baseline and more resistant to the disruptive effects of intercomponent food and extinction. Forgetting functions were constructed by examining matching accuracy as a function of delay duration. Baseline accuracy was higher in the rich component than in the lean component as measured by differences in the gamma-intercept of the forgetting functions (i.e., initial discrimination), rather than from differences in the slope of the forgetting function (i.e., rate of forgetting). Intercomponent food increased the rate of forgetting relatively more in the lean component than in the rich component, but initial discrimination was not systematically affected. Extinction reduced initial discrimination relatively more in the lean component than in the rich component, but did not systematically affect rate of forgetting. These results are consistent with our previous data suggesting that, as for response rate, accuracy and resistance to change of discriminating are positively related to rate of reinforcement. These data also suggest that the disruptability of remembering depends on the conditions of reinforcement, but the way in which remembering is disrupted depends on the nature of the disruptor.