Stimulus and reinforcer relativity in multiple schedules: Local and dimensional effects on sensitivity to reinforcement

Pigeons' responses in two successive components of multiple schedules were reinforced according to variable-interval schedules of reinforcement that varied over five different conditions. Within each session of all conditions, line orientations of 0°, 30°, or 45° in Component 1 alternated with orientations of 45°, 60°, or 90° in Component 2. Response rates were recorded in three successive subintervals of each component. Ratios were taken between the response rate in each Component 1 line orientation and the response rate in each Component 2 orientation. These ratios were found to be power functions of the corresponding ratios of obtained reinforcement rates. Sensitivity of response ratios to changes in reinforcer ratios, given by the value of the exponent of the power function, increased systematically with increasing disparity between the dimensional values of orientation stimuli. In addition, sensitivity decreased systematically over successive subintervals of components, that is, with increasing time since component alternation. Dimensional and local (subinterval) effects interacted in that sensitivity increased with stimulus disparity to a far greater extent in the first subinterval than later in components. The data could be described by a combination of rectangular hyperbolae which attributed the interaction between local and dimensional effects to limits set by local effects on the extent that stimulus differences could affect sensitivity.     

Why a common commemoration of the Reformation?

This article provides information about the fact that today any commemoration of the Reformation can only be celebrated in ecumenical communion. In contrast to earlier Reformation jubilees, the commemoration of the Reformation in 2017 is taking place, for the first time, in an ecumenical era. The year 2017 refers back to the year 1517, that is, to a time when the break with the Catholic Church had not yet happened. Martin Luther himself did not intend the division of the Church, nor did he visualise the founding of a new church, but the renewal of all Christendom. This failed in his time. Therefore one should regard the ecumenical search for the restoration of unity as the – indeed very belated – success of the Reformation. The commemoration of ??a reformation is an ecumenical opportunity, if it is committed to living the triad of gratitude for the reformation’s positive aims, of repentance for the sins of division and subsequent confessional wars, and of hope for a greater unity between Lutherans and Catholics.     

Body weight and response acquisition with delayed reinforcement.

The relation between body weight and responding established with unsignaled delayed reinforcement was investigated. In three experiments, naive rats were deprived to either 70%, 80%, or 90% of ad libitum weight and were then exposed to tandem variable-interval 15-s differential-reinforcement-of-other-behavior 30-s schedules. The tandem schedule defined a resetting unsignaled delay-of-reinforcement procedure. In the first experiment, speed of magazine training, acquisition of lever pressing, and final rate of lever pressing were related to body weight. In the next experiment, lever pressing was established and maintained in rats that were magazine trained at 70% of ad libitum weight but that were then exposed to the delay procedure at 90% of ad libitum weight. Responding did not change consistently either across or within subjects in subsequent conditions in which body weight was manipulated. In the final experiment, lever pressing was established and maintained with delayed reinforcement in the absence of magazine training for each of 2 rats at 70% and for 1 of 2 rats at 90% of ad libitum weight. The results further illuminate the conditions under which responding can be established in the absence of training and when such responses are reinforced only following an unsignaled delay period.     

Concurrent variable-interval variable-ratio schedules can provide only weak evidence for matching

Herrnstein and Heyman (1979) showed that when pigeons' pecking is reinforced on concurrent variable-interval variable-ratio schedules, (1) their behavior ratios match the ratio of the schedules' reinforcer frequencies, and (2) there is more responding on the variable interval. Since maximizing the reinforcement rate would require responding more on the variable ratio, these results were presented as establishing the primacy of matching over maximizing. In the present report, different ratios of behavior were simulated on a computer to see how they would affect reinforcement rates on these concurrent schedules. Over a wide range of experimenter-specified choice ratios, matching obtained — a result suggesting that changes in choice allocation produced changes in reinforcer frequencies that correspond to the matching outcome. Matching also occurred at arbitrarily selected choice ratios when reinforcement rates were algebraically determined by each schedule's reinforcement-feedback function. Additionally, three birds were exposed to concurrent variable-interval variable-ratio schedules contingent on key pecking in which hopper durations were varied in some conditions to produce experimenter-specified choice ratios. Matching generally obtained between choice ratios and reinforcer-frequency ratios at these different choice ratios. By suggesting that reinforcer frequencies track choice on this procedure, instead of vice versa, this outcome questions whether matching-as-outcome was due to matching-as-process in the Herrnstein and Heyman study.     

The effects of unsignalled delayed reinforcement

Pigeons' pecks were reinforced according to a variable-interval schedule. A delay-of-reinforcement procedure was then added to the schedule, or a yoked-control procedure was arranged where the reinforcers occurred independently of responding according to the same variable-interval schedule. During the delay-of-reinforcement procedure, the first peck after a reinforcer was scheduled began a delay timer and the reinforcer was delivered at the end of the interval. No stimulus change signalled the delay interval and responses could occur during it, so that the obtained delays were often shorter than those scheduled. Responding under this procedure was highly variable but, in general, behavior was substantially reduced even with the shortest delay used, 3 sec. In addition, the rates maintained by delayed reinforcement were only slightly greater than those maintained by the yoked-control procedure, suggesting that adventitious pairings of response and reinforcer were responsible for some of the maintenance of behavior that did occur. The results challenge recent conceptions of reinforcement as involving response-reinforcer correlations and re-emphasize the role of temporal proximity between response and reinforcer.     

Molar versus local reinforcement probability as determinants of stimulus value.

During one component of a multiple schedule, pigeons were trained on a discrete-trial concurrent variable-interval variable-interval schedule in which one alternative had a high scheduled rate of reinforcement and the other a low scheduled rate of reinforcement. When the choice proportion between the alternatives matched their respective relative reinforcement frequencies, the obtained probabilities of reinforcement (reinforcer per peck) were approximately equal. In alternate components of the multiple schedule, a single response alternative was presented with an intermediate scheduled rate of reinforcement. During probe trials, each alternative of the concurrent schedule was paired with the constant alternative. The stimulus correlated with the high reinforcement rate was preferred over that with the intermediate rate, whereas the stimulus correlated with the intermediate rate of reinforcement was preferred over that correlated with the low rate of reinforcement. Preference on probe tests was thus determined by the scheduled rate of reinforcement. Other subjects were presented all three alternatives individually, but with a distribution of trial frequency and reinforcement probability similar to that produced by the choice patterns of the original subjects. Here, preferences on probe tests were determined by the obtained probabilities of reinforcement. Comparison of the two sets of results indicates that the availability of a choice alternative, even when not responded to, affects the preference for that alternative. The results imply that models of choice that invoke only obtained probability of reinforcement as the controlling variable (e.g., melioration) are inadequate.     

Interresponse-time analysis of stimulus control in multiple schedules

Interresponse-time distributions were recorded in two components of multiple variable-interval schedules that were varied over several conditions. Values of the exponent for power functions relating ratios of interresponse times emitted per opportunity to ratios of reinforcers obtained in the two components varied with interresponse-time class interval. The exponent (sensitivity to reinforcement) afforded a measure of stimulus control exerted by the discriminative stimuli. Exponents were near zero for short interresponse times, consistent with previous conclusions that responses following short interresponse times are controlled by response-produced or proprioceptive stimuli. Values of exponents increased with longer interresponse times, indicating strong control by exteroceptive stimuli over responses following interresponse times of approximately one second or longer.     

Decision making in a case of mixed uncertainty: A normative model

We consider a case of uncertainty which is frequently met in various fields, e.g., in parametric statistics: Events {θ}, θ ∈ ∵, are members of family $\text{E}$ on which the decision maker possesses no information at all; however, conditionally on the realization of {θ}, he is able to affix probabilities to all members of another family of events, $\text{F}$. We assume that the decision maker: (1) has a rational behavior under complete ignorance, for decisions whose results only depend on events of $\text{E}$; (2) with {θ} known, maximizes his conditional expected utility for decisions whose results only depend on events of $\text{F}$; (3) has (unconditional) preferences which are consistent with his conditional ones. These assumptions are shown to be sufficient to ensure an approximate representation of the decision maker's preference by a real-valued function W which has the form $\text{W(f) = v[}\text{Inf}{}_{\mathrm{\theta \in \because }}\text{E}{}_{\mathrm{\theta }}\text{(u°f),}\text{Sup}{}_{\mathrm{\theta \in \because }}\text{E}{}_{\mathrm{\theta }}\text{(u°f)]}$, where u and v, respectively, characterize the decision maker's attitudes toward risk and toward complete ignorance.     

Two kings and two kingdoms: the Church of Scotland,the monarchy,national identity and establishment

The debate about Scottish independence raises questions about church–state relations and religious establishment in Scotland as well as about national identity. This article surveys and summarises attitudes in the Church of Scotland on these subjects over the 450 years since the Scottish Reformation. It identifies and explores several key themes, notably the spiritual independence of the church and national recognition of religion. They were hotly debated topics during the reign of King James VI, enshrined in law in the aftermath of the Glorious Revolution and prompted the use of the royal veto by Queen Victoria. The Articles Declaratory of the Church of Scotland, embodied in the Church of Scotland Act of 1921, which provide a unique definition of church establishment, will have to be renegotiated in the event of Scottish independence. There are competing views within the Kirk about the constitutional position of Christianity and more specifically of the Church of Scotland in an independent Scotland.     

难度与分值对高一学生选择停止、集中或分散学习的影响

选取50名高一学生,选用反义词对和人工词对两种学习材料,赋予学习材料不同的分值,探讨项目难度和分值对学习者集中学习或分散学习选择及其效果的影响,并通过问卷调查被试对不同学习方式的认识。结果发现:(1)只有44%的被试报告分散学习更有效,被试总体上也更多地选择了集中学习;(2)在困难项目上,分散学习比集中学习的效果更好;(3)被试对容易项目更多选择停止学习,对困难项目更少选择停止学习,特别是困难高分项目;对困难项目比对容易项目更多选择分散学习,而在困难与容易项目上,对集中学习的选择不存在显著差异。