Variable-ratio conditioning history produces high- and low-rate fixed-interval performance in rats

Four rats were exposed to an A-B-A-B series of 30 sessions each of variable-ratio 20 (A) and fixed-interval 30-s (B) schedules. Four other rats received 120 sessions of fixed-interval 30 s. The rats with a history of variable-ratio responding subsequently showed primarily high or low response-rate patterns on the fixed-interval schedule without evidence of classical scalloping (i.e., increased rates of responding throughout the interreinforcement interval), except infrequently in 1 rat. The rats exposed to only the fixed-interval 30-s schedule displayed the expected sequence of scalloping giving way to lower rate break-run or simply low-rate responding over time. This experiment shows that when naive rats are exposed to even a simple history of reinforcement (in this case, a variable-ratio 20), their subsequent fixed-interval performance is very different from comparable performance in naive rats, and might be said to be more similar to the responding of adult humans. The argument is made that care should be taken in comparing the fixed-interval performance of humans and nonhumans because humans have a complex history of reinforcement, whereas laboratory nonhumans are typically naive.     

A functional approach for research on cognitive control: Analysing cognitive control tasks and their effects in terms of operant conditioning

Cognitive control is an important mental ability that is examined using a multitude of cognitive control tasks and effects. The present paper presents the first steps in the elaboration of a functional approach, which aims to uncover the communalities and differences between different cognitive control tasks and their effects. Based on the idea that responses in cognitive control tasks qualify as operant behaviour, we propose to reinterpret cognitive control tasks in terms of operant contingencies and cognitive control effects as instances of moderated stimulus control. We illustrate how our approach can be used to uncover communalities between topographically different cognitive control tasks and can lead to novel questions about the processes underlying cognitive control.     

Impact of outpatient non-myeloablative haematopoietic stem cell transplantation in quality of life vs. conventional therapy

The role of outpatient hematopoietic stem cell transplantation (HSCT) as a therapeutic tool has been strengthened significantly because of the increasing number of patients undergoing this treatment. Due the very nature of this procedure, one of the aspects that should not be overlooked is the quality of life (QOL) of patients undergoing HSCT. Thus, one must consider not only health status after treatment, but also, the psychosocial implications for the patient. This is an observational, longitudinal, and prospective study to assess QOL in patients undergoing outpatient HSCT vs. similar patients receiving medical treatment (MxTx). By applying the COOP/WONKA charts on five occasions (pre-HSCT/initial, post-HSCT/first month, and at 3, 6, and 9 months), thirty-eight patients were analysed, 19 with HSCT and 19 with MxTx with no differences in age, gender or diagnosis. The initial survey found significant differences only in pain perception, which was higher in the HSCT group (p = .08); at the first month, there was a greater tendency for feelings of depression or anxiety in the HSCT group (p = .016), with more limitations in social (p = .003) and daily (p = .044) activities. From 3 months post-HSCT, the results were very similar. The differences persisted only in the area of social activities. Four patients developed graft-versus-host disease with no significant difference in the scores obtained compared to other transplant patients at 3, 6, and 9 months (p = .26) of follow-up.     

Within-session Changes In Responding During Autoshaping And Automaintenance Procedures

Four pigeons were exposed to autoshaping procedures in which an 8-second light on a response key was followed by food. Pecks on the key had no scheduled consequences. Subjects were also exposed to negative automaintenance procedures in which a peck on the illuminated key canceled the following food. The intertrial interval varied from an average of 7 seconds to an average of 232 seconds in different conditions. Rate of responding usually changed within sessions during autoshaping. Responding also changed within sessions for the 1 subject that responded during negative automaintenance. The within-session patterns of responding were flatter, peaked later, and were more symmetrical around the middle of the sessions at lower rates of food presentation, regardless of whether subjects responded on autoshaping, negative automaintenance, or previously reported variable-interval schedules. These results imply that similar variables produce within-session changes in responding during both classical (Pavlovian) and operant conditioning procedures.     

恐惧情绪对大鼠学习记忆的影响

通过对４组不同处理背景动物操作条件学习的实验研究,观察强噪音下恐惧情绪对动物学习、记忆的影响以及怎样通过系统脱敏来减少恐惧在其中的作用。结果发现：恐惧组大鼠的操作条件学习具有第一次联系（健盘与食物之间）成功所需时间短、旧技能遗忘快、重新学习次数多和学习成绩差等特征;恐惧组大鼠与学习无关的恐惧行为增多,严重干扰学习的控制加工过程,影响学习任务完成;强噪音脱敏组大鼠学习过程、学习成绩的各项指标与控制组无差异。     

Contribution of Ventrolateral Prefrontal Cortex to the Acquisition and Extinction of Conditioned Fear in Rats

The ventrolateral, agranular insular portion of prefrontal cortex (PFC) in rats is involved in visceral functions and has been shown to be involved in emotional processes. However, its contribution to aversive learning has not been well defined. Classical fear conditioning has been a powerful tool for illuminating some of the primary neural structures involved in aversive emotional learning. We measured both the acquisition and the extinction of conditioned fear following lesions of the ventrolateral PFC of rats. Lesions reduced fear reactivity to contextual stimuli associated with conditioning without affecting CS acquisition, and had no effect on response extinction. Ventrolateral PFC may normally be involved in the processing of contextual information while not being directly involved in extinction processes within the aversive domain.     

Correspondence training, prior verbal training, and control of nonverbal behavior via control of verbal behavior

The role of prior verbal training in correspondence training and later verbal control of nonverbal behavior was examined in two groups of Head Start children. One group received correspondence training without prior verbal training, the other with. Essentially no differences were found between the two sequences; thus it seems appropriate to consider the content phases (reinforcement contingent on target verbalization alone) of previous research as control procedures and not a necessary precursor to correspondence training.     

Conditioned orienting and defensive responses in the developing rat

Infant rats (16, 21, and 26 days old) received 3 days of classical conditioning training to Tone/Shock pairings using heart rate as the index of conditioning. The youngest group (16 days old) showed no evidence of conditioning at any stage of acquisition. In the 21- and 26-day-olds, response to the conditioned stimulus (CS) was a deceleration in heart rate during the first day of training. By day 3, the conditioned response (CR) shifted to cardioacceleration. The data were interpreted as offering strong support for a two-stage model of information processing in the infant rat, comprised of a conditioned orienting response in the first stage and a conditioned defensive response in the second.     

Effects of prompting and reinforcement of one response pattern upon imitation of a different modeled pattern

Twelve preschool children participated in a study of the effects of explicit training on the imitation of modeled behavior. The responses trained involved a marble-dropping pattern that differed from the modeled pattern. Training consisted of physical prompts and verbal praise during a single session. No prompts or praise were used during test periods. After operant levels of the experimental responses were measured, training either preceded or was interposed within a series of exposures to modeled behavior that differed from the trained behavior. Children who were initially exposed to a modeling session immediately imitated, whereas those children who were initially trained immediately performed the appropriate response. Children initially trained on one pattern generally continued to exhibit that pattern even after many modeling sessions. Children who first viewed the modeled response and then were exposed to explicit training of a different response reversed their response pattern from the trained response to the modeled response within a few sessions. The results suggest that under certain conditions explicit training will exert greater control over responding than immediate modeling stimuli.