Contingent Stimuli Signal Subsequent Reinforcer Ratios

Conditioned reinforcer effects may be due to the stimulus' discriminative rather than its strengthening properties. While this was demonstrated in a frequently‐changing choice procedure, a single attempt to replicate in a relatively static choice environment failed. We contend that this was because the information provided by the stimuli was nonredundant in the frequently‐changing preparation, and redundant in the steady‐state arrangement. In the present experiments, 6 pigeons worked in a steady‐state concurrent schedule procedure with nonredundant informative stimuli (red keylight illuminations). When a response‐contingent red keylight signaled that the next food delivery was more likely on one of the two alternatives, postkeylight choice responding was reliably for that alternative. This effect was enhanced after a history of extended informative red keylight presentation (Experiment 2). These results lend support to recent characterizations of conditioned reinforcer effects as reflective of a discriminative, rather than a reinforcing, property of the stimulus.     

Examining the discriminative and strengthening effects of reinforcers in concurrent schedules

Reinforcers may increase operant responding via a response-strengthening mechanism whereby the probability of the preceding response increases, or via some discriminative process whereby the response more likely to provide subsequent reinforcement becomes, itself, more likely. We tested these two accounts. Six pigeons responded for food reinforcers in a two-alternative switching-key concurrent schedule. Within a session, equal numbers of reinforcers were arranged for responses to each alternative. Those reinforcers strictly alternated between the two alternatives in half the conditions, and were randomly allocated to the alternatives in half the conditions. We also varied, across conditions, the alternative that became available immediately after a reinforcer. Preference after a single reinforcer always favored the immediately available alternative, regardless of the local probability of a reinforcer on that alternative (0 or 1 in the strictly alternating conditions, .5 in the random conditions). Choice then reflected the local reinforcer probabilities, suggesting some discriminative properties of reinforcement. At a more extended level, successive same-alternative reinforcers from an alternative systematically shifted preference towards that alternative, regardless of which alternative was available immediately after a reinforcer. There was no similar shift when successive reinforcers came from alternating sources. These more temporally extended results may suggest a strengthening function of reinforcement, or an enhanced ability to respond appropriately to "win-stay" contingencies over "win-shift" contingencies.     

Human responding with mutual reinforcement: Baseline and effects of an intervention1

Pressing a key by one undergraduate provided another undergraduate with points exchangeable for money, and vice versa. Four types of response patterns were found. Points were often delivered with a delay from the last response or with no response. When a contingency that responses lost points (punishment) was added to participants who had emitted more responses than the partner had, their response rates decreased while the rates of their partners increased. These results demonstrate that, under the contingency of mutual reinforcement: (a) response patterns that had occurred between monkeys were replicated between humans; (b) obtained response‐reinforcer relations were different from those generally programmed in the basic reinforcement schedules; and (c) the behavior of the participant was controlled by changing the behavior of the partner.     

RISKY CHOICE IN PIGEONS: PREFERENCE FOR AMOUNT VARIABILITY USING A TOKEN-REINFORCEMENT SYSTEM

Pigeons were given repeated choices between variable and fixed numbers of token reinforcers (stimulus lamps arrayed above the response keys), with each earned token exchangeable for food. The number of tokens provided by the fixed‐amount option remained constant within blocks of sessions, but varied parametrically across phases, assuming values of 2, 4, 6, or 8 tokens per choice. The number of tokens provided by the variable‐amount option varied between 0 and 12 tokens per choice, arranged according to an exponential or rectangular distribution. In general, the pigeons strongly preferred the variable option when the fixed option provided equal or greater numbers of tokens than the variable amount. Preference for the variable amount decreased only when the alternatives provided widely disparate amounts favoring the fixed amount. When tokens were removed from the experimental context, preference for the variable option was reduced or eliminated, suggesting that the token presentation played a key role in maintaining risk‐prone choice patterns. Choice latencies varied inversely with preferences, suggesting that local analyses may provide useful ancillary measures of reinforcer value. Overall, the results indicate that systematic risk sensitivity can be attained with respect to reinforcer amount, and that tokens may be critical in the development of such preferences.     

Effects of pre-trial response requirements on self-control choices by rats and pigeons

Parallel experiments with rats and pigeons examined whether the size of a pre-trial ratio requirement would affect choices in a self-control situation. In different conditions, either 1 response or 40 responses were required before each trial. In the first half of each experiment, an adjusting-ratio schedule was used, in which subjects could choose a fixed-ratio schedule leading to a small reinforcer, or an adjusting-ratio schedule leading to a larger reinforcer. The size of the adjusting ratio requirement was increased and decreased over trials based on the subject's responses, in order to estimate an indifference point-a ratio at which the two alternatives were chosen about equally often. The second half of each experiment used an adjusting-delay procedure-fixed and adjusting delays to the small and large reinforcers were used instead of ratio requirements. In some conditions, particularly with the reinforcer delays, the rats had consistently longer adjusting delays with the larger pre-trial ratios, reflecting a greater tendency to choose the larger, delayed reinforcer when more responding was required to reach the choice point. No consistent effects of the pre-trial ratio were found for the pigeons in any of the conditions. These results may indicate that rats are more sensitive to the long-term reinforcement rates of the two alternatives, or they may result from a shallower temporal discounting rate for rats than for pigeons, a difference that has been observed in previous studies.     

Preference for gamma-hydroxybutyrate (GHB) in current users

Gamma-hydroxybutyrate (GHB) is a drug with significant abuse potential. The present study aimed to assess the relative value of escalating doses of GHB to current GHB users via the Multiple Choice Procedure (MCP), and to validate that the dose rated highest with the MCP would be self-administered at a greater rate than placebo. Participants were 5 current GHB users who were not currently trying to stop using GHB. To examine the value of escalating doses of GHB, the following doses of GHB were used: 0 (placebo), 12.5, 25, 37.5, and 50 mg/kg. Participants typically assigned higher doses of GHB had higher crossover points on the MCP. During choice sessions, participants made repeated choices between administering GHB, placebo or nothing. All participants selected GHB exclusively (5 out of 5 instances) except for one participant who selected GHB on 4 out of 5 instances, thus 96% (i.e., 24/25) of choices were for active GHB. Based on these data, GHB appears likely to function as a dose-dependent reinforcer for humans based on our sample.     

外科病理学超越自我发展的思考

病理学是一门以组织形态学研究为基础的学科,经历了二百多年的发展历程。外科病理学作为病理学的重要部分,密切联系临床,以临床需要为方向,在医疗活动中充当着重要的角色,发挥着重要作用。随着免疫组织技术、基因芯片及组织芯片技术、图像分析技术、数字化图像技术、网络技术、流式细胞学技术等出现和应用,外科病理学在医疗活动中的权重日益增加,其中很多内容已远远超出病理形态学本身,向细胞分子,DNA,基因改变方向发展。     

国外自杀心理学研究与理论评介

以自杀致病理论、自杀评估理论、自杀治疗理论为线索,回顾与总结了国外近十年来的自杀心理学理论与研究概况,同时重点介绍了致病理论中的应激—易感模型、逃避自我理论、杀死自我理论;自杀评估理论中的SSF评估、四阶段过程模式;自杀治疗理论中的SATIR理论和荣格艺术治疗理论等,并做了简短评论     

Reinforcer choice as an antecedent versus consequence

Four children with autism received opportunities to choose among several preferred stimuli either immediately before or after task responding. The response requirement for reinforcement systematically increased within each session. Two children engaged in higher levels of responding when reinforcement choice was provided as an antecedent to task completion, and 3 of the 4 children showed a preference for the antecedent choice condition.     

Problematic mobile phone use as impulsive choice: Development and empirical verification of a reinforcer-pathology model

Problematic mobile phone use is characterized by its “impulsive” nature; users engage in it despite their negative attitude toward it. From a behavioral-economic perspective, this attitude–behavior discrepancy is generated by competing contingencies that involve smaller-sooner social reinforcers associated with mobile phone use and larger-later prosocial reinforcers potentially compromised by phone use. Based on this conceptualization, the reinforcer-pathology model of problematic mobile phone use is proposed, which posits that such phone use stems from excessive delay discounting of the social and prosocial reinforcers and/or excessive demand for the social reinforcers. A secondary data analysis of previously published studies was conducted, with the novel addition of principal component analysis and hierarchical cluster analysis of these data. The results generated evidence that supports the reinforcer-pathology model proposed in this article. Based on the theoretical analyses and accumulated empirical evidence, theory-driven prevention and intervention strategies for problematic mobile phone use are proposed. Overall, the reinforcer-pathology model of problematic mobile phone use provides a comprehensive framework for understanding and addressing this growing issue.