TEMPORAL CONTROL ON INTERVAL SCHEDULES: WHAT DETERMINES THE POSTREINFORCEMENT PAUSE?

On fixed-interval or response-initiated delay schedules of reinforcement, the average pause following food presentation is proportional to the interfood interval. Moreover, when a number of intervals of different durations occur in a programmed cyclic series, postreinforcement pauses track the changes in interval value. What controls the duration of postreinforcement pauses under these conditions? Staddon, Wynne, and Higa (1991), in their linear waiting model, propose control by the preceding interfood interval. Another possibility is that delay to reinforcement, signaled by a key peck and/or stimulus change, determines the subsequent pause. The experiments reported here examined the role of these two possible time markers by studying the performance of pigeons under a chained cyclic fixed-interval procedure. The data support the linear waiting model, but suggest that more than the immediately preceding interfood interval plays a role in temporal control.     

The effects of narrative context on French verbal inflections: A developmental perspective

This experiment examines how narrative context affects French subjects' selection of past imperfective (imparfait) vs. perfective inflections with different predicate types. Adults and 10-year-old children were asked to inflect verbs presented in their written infinitive form in two conditions: (a) in isolated sentences; (b) embedded in the beginning, middle, or end of narratives. Regardless of conditions, the adults rarely used theimparfait with punctual resultative predicates. In both conditions, the frequency ofimparfait was high with durative predicates, particularly with aresultative ones, but it varied with position in the narratives, being highest at the beginning and lowest at the end. Although the children also used the imparfait frequently with durative predicates, they overgeneralized it to punctual resultative ones, regardless of conditions and of positions. These results show that adult uses of the imperfective/perfective distinction are determined by both predicate properties and grounding in narrative context. The children are less sensitive to some predicate properties than the adults and they do not differentiate imperfective/perfective aspect consistently as a function of discourse context.     

Choice between delayed reinforcers and fixed-ratio schedules requiring forceful responding.

This experiment measured pigeons' choices between delayed reinforcers and fixed-ratio schedules in which a force of approximately 0.48 N was needed to operate the response key. In ratio-delay conditions, subjects chose between a fixed-ratio schedule and an adjusting delay. The delay was increased or decreased several times a session in order to estimate an indifference point--a delay duration at which the two alternatives were chosen about equally often. Each ratio-delay condition was followed by a delay-delay condition in which subjects chose between the adjusting delay and a variable-time schedule, with the components of this schedule selected to match the ratio completion times of the preceding ratio-delay condition. The adjusting delays at the indifference point were longer when the alternative was a fixed-ratio schedule than when it was a matched variable-time schedule, which indicated a preference for the matched variable-time schedules over the fixed-ratio schedules. This preference increased in a nonlinear manner with increasing ratio size. This nonlinearity was inconsistent with a theory that states that indifference points for both time and ratio schedules can be predicted by multiplying the choice response-reinforcer intervals of the two types of schedules by different multiplicative constants. Two other theories, which predict nonlinear increases in preference for the matched variable-time schedules, are discussed.     

Unification of models for choice between delayed reinforcers.

Two models for choice between delayed reinforcers, Fantino's delay-reduction theory and Killeen's incentive theory, are reviewed. Incentive theory is amended to incorporate the effects of arousal on alternate types of behavior that might block the reinforcement of the target behavior. This amended version is shown to differ from the delay-reduction theory in a term that is an exponential in incentive theory and a difference in delay-reduction theory. A power series approximation to the exponential generates a model that is formally identical with delay-reduction theory. Correlations between delay-reduction theory and the amended incentive theory show excellent congruence over a range of experimental conditions. Although the assumptions that gave rise to delay-reduction theory and incentive theory remain different and testable, the models deriving from the theories are unlikely to be discriminable by parametric experimental tests. This congruence of the models is recognized by naming the common model the delayed reinforcement model, which is then compared with other models of choice such as Killeen and Fetterman's (1988) behavioral theory of timing, Mazur's (1984) equivalence rule, and Vaughan's (1985) melioration theory.     

Metaphysics of causation

Conclusion The world contains not only causes and effects, but also causal relations holding between causes and effects. Because causal relations enter into the structure of the world, their presence has various modal and probabilistic consequences. Causation and necessary and sufficient conditions do often go hand in hand. Causation, however, is a robust ingredient within the world itself, whereas modalities and probabilities supervene on the nature of the world as a whole, and on the resulting relations between one possible world and others. Some modalities, therefore, are essentially causal; but causation is not essentially modal.¹⁹     

汉语句子的多层次分析

本文试图建立一个中文句子分析的计算机模型。在该模型中,句法、语义信息对中文句子的多层次分析是同等重要的。为此,我们提出了一些语义规则,利用这些规则可将语义关系综合进句法和词典,使该模型能同时进行不同层次的加工。对汉语一些典型句型的应用表明,该模型是行之有效的。     

句子理解的实验研究

在三种不同的条件下,对人验证句子的过程作了比较研究。结果表明,无论在哪种条件下,验证不同类型句子的时间模式是一致的。在句子-图形验证任务中,不管这些图形是抽象的符号还是与常识有关的具体事物的图形,其加工所需的时问基本上是相同的。但是,句子-常识验证所需的时间,要比句子-图形验证的时间明显地短。实验还表明,否定词在句中的位置,对句子的理解有一定的影响。     

特殊青少年感觉寻求特质的研究

本文对优秀少年、少年犯和普通少年进行了感觉寻求特质、认知复杂性、棒框测验和心率的研究。旨在检验和证实F.Farley的有关理论:高感觉寻求者由于寻求刺激方式的不同而具有两种不同的行为倾向;并深入探讨不同少年的认知和生理特点。实验结果表明,少年犯和优秀少年比普通少年具有更高的感觉寻求倾向。优秀少年和少年犯寻求刺激的方面是不同的。优秀少年的认知复杂性分数较高,并倾向于场独立性特征,对新异刺激倾向于朝向反射特点;少年犯则具有较低的认知复杂性和场依存性特征。     

Overt responding in computer-based training

This experiment compared the extent to which students learned facts included in computer-based-training frames that required an overt response to those that did not. Frames included two types of facts: Some facts had one word missing which had to be supplied by the student (active facts). Other facts had no missing words and required no overt response (passive facts). Each student completed four 14-fact modules in random order. Two of the modules contained frames with all active facts. Each frame in the other two modules contained one active and six passive facts. Paper pretests and posttests showed that students learned twice as many facts when all facts in the module were active than when only one in seven were active. The modules that included passive facts required one-fifth the time to complete than those with only active facts. Students learned more facts per minute of training in one of the two modules that included passive facts than in the two modules with only active facts.