Deprivation level and choice in pigeons: a test of within-trial contrast

Within-trial contrast has been proposed as a mechanism underlying preferences for stimuli that follow relatively more aversive events over stimuli that follow less aversive events. In this study, we manipulated deprivation level to test within-trial contrast predictions. In Experiment 1, pigeons encountered two discriminative stimuli, one presented when they were deprived and the other when they were prefed. When later given a choice between the two stimuli, pigeons strongly preferred the stimulus encountered when deprived, independently of their deprivation level at test. In Experiment 2, pigeons learned two simultaneous discriminations, one when deprived and the other when prefed. Here, subsequent tests between the two S⁺ or the two S⁻ stimuli revealed no consistent preferences. These contrasting findings suggest that differential aversiveness is necessary but not sufficient to induce preferences via within-trial contrast.     

Behavioral contrast and reinforcement value

Behavioral contrast was produced in two target components of a four-component multiple schedule by having two target stimuli followed either by a higher rate of reinforcement or by extinction. Response rate was higher in the target followed by extinction. Periodic probe trials were then presented in which the two target stimuli were presented together. Choice on these probe trials was in favor of the stimulus followed by the higher rate of reinforcement during regular training. Experiment 2 replicated this finding but with probe trials presented throughout training. Here, preference for the stimulus followed by the higher rate of reinforcement was evident early in training, substantially before the contrast effects developed. The results challenge interpretations of contrast based on the concept of relative value.     

Behavioral contrast and inhibitory stimulus control

Two experiments examined the presumed relationship between behavioral contrast and inhibitory stimulus control. In Experiment I, pigeons were exposed to mult VI 1-min VI 1-min or mult VI 5-min VI 5-min during baseline training prior to mult VI 1-min VI 5-min discrimination training. Half of the subjects received a timeout (TO) component during baseline in order to reduce the degree of contrast during discrimination training. Only 3 of 8 subjects receiving the TO showed contrast while all other subjects showed various degrees of contrast. Postdiscrimination generalization gradients indicated excitatory rather than inhibitory control by the stimulus associated with the VI 5-min schedule. During baseline training in Experiment II, responding to all the generalization stimuli was reinforced. In addition, some subjects received the TO stimulus. The subjects were next exposed to mult VI 1-min EXT, mult VI 1-min VI 5-min, or just the VI 5-min component. Generalization gradients indicated inhibitory control by the stimulus associated with EXT or VI 5-min for 19 of 20 subjects even though some subjects did not show contrast. These results question the presumed relationship between behavioral contrast and inhibitory stimulus control.     

Determinants of value transfer and contrast in simultaneous discriminations by pigeons

In a simultaneous discrimination involving a positive (S+) and a negative (S₋) stimulus, positive value appears to transfer from the S+ to the S₋. However, negative value does not appear to transfer from the S₋ to the S+. Instead, when sufficient experience with the contingencies associated with responding to the S₋ is provided, it appears that the presence of the S₋ enhances the value of the S+ (i.e., a contrast effect is found). The purpose of the present experiments was to further examine the influence of the S+ on the S₋ in a simultaneous discrimination (between subjects in Experiment 1 and within subjects in Experiment 2). In both experiments, we found that under typical training conditions, given little direct experience with the value of the S₋, value transfers from the S+ to the S₋. If sufficient experience with the value of the S₋ is provided, however, contrast between the S+ and the S₋ can be demonstrated. Thus, in a simultaneous discrimination, value transfer from the S+ to the S₋ depends on the animal’s having responded relatively little to the S₋.     

Behavioral contrast and type of reward: Role of elicited response topography

Groups of pigeons were exposed to multiple variable-interval variable-interval and multiple variable-interval extinction schedules of either food or water reinforcement for keypecking. Discriminative stimuli associated with component schedules were located either on the operant key or on a second “signal” key. When the stimuli were projected on the operant key, positive contrast appeared during discrimination conditions with either food or water as the reinforcer. When the stimuli were projected on the signal key, overall responding to the operant and signal keys showed contrast with food, but negative induction with water as the reinforcer. In the latter condition, the signal for the variable-interval shcedule of water reinforcement elicited a variety of water-related behavior, only some of which was directed at the signal. Thus, the type of reward and location of discriminative stimuli interacted to determine the presence or absence of behavioral contrast effects. In large part, these results support and extend the autoshaping view of contrast.     

Why educational reforms fail: A comparative analysis

The paper reviews a number of educational policy statements of East African countries ranging from combining education with production at the primary level, to the financing of higher education. An assessment is made of how successful the policies have been in achieving their original intention. The paper's conclusion is that policy outcomes are far from matching expectations, mainly because of insufficient or no implementation. The reason most educational policies are not implemented is that they are vaguely stated and the financing implications are not always worked out. Another reason for failure is that the content of a policy is based on an empirically unsustained theoretical relationship between instruments and outcomes. The paper makes a plea for the formulation of more concrete, feasible and implementable policies based on documented cause-effect relationships.

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Zusammenfassung In dem Artikel werden eine Reihe von erziehungspolitischen Aussagen ostafrikanischer Länder untersucht. Sie reichen von der Verbindung der Erziehung mit der Produktion auf der Grundstufe bis hin zur Finanzierung der Hochschulausbildung. Es wird eine Bestandsaufnahme gemacht hinsichtlich des Erfolgs, der den erziehungspolitischen Programmen beim Erreichen ihrer ursprünglichen Ziele beschieden war, wobei man zu dem Schluß kommt, daß die Resultate der Programme hauptsächlich dadurch, daß diese nicht oder nur unzureichend durchgeführt wurden, weit davon entfernt sind, die Erwartungen zu erfüllen. Der Grund dafür, daß die meisten erziehungspolitischen Programme nicht durchgeführt werden, liegt darin, daß sie nur vage umrissen und die finanziellen Auswirkungen nicht immer ausgearbeitet sind. Ein weiterer Grund für ihr Fehlschlagen liegt darin, daß der Inhalt eines Programms auf einer empirisch unhaltbaren theoretischen Beziehung zwischen Mitteln und Resultaten basiert. In dem Artikel wird daher für die Formulierung konkreterer, geeigneterer und durchführbarerer Programme plädiert, die auf bereits belegten Beziehungen von Ursache und Wirkung beruhen.

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Résumé Le présent article examine quelques déclarations de pays de l'Afrique orientale relatives à la politique éducative, allant d'un système combiné d'éducation et de travail productif dans l'enseignement primaire, au financement de l'enseignement supérieur. Une analyse est effectuée pour savoir combien ces politiques ont réussi à mettre en oeuvre leur objectif premier. Cet article conclut que les résultats de ces politiques sont loin de répondre aux exigences, en raison essentiellement d'une mise en oeuvre insuffisante, voire nulle. La raison pour laquelle la plupart des politiques éducatives ne sont pas appliquées est due au fait qu'elles sont vaguement formulées et les implications financières rarement élaborées. La seconde raison de cet échec est que le contenu d'une politique se fonde sur une relation théorique entre instruments et résultats qui n'a pas été vérifiée empiriquement. Cet article plaide en faveur de politiques concrètes, réalisables et applicables fondées sur un rapport de cause à effet bien documenté.

     

Anticipatory contrast: Within-subjects analysis

Contrast in consummatory behavior occurs readily when a less preferred substance follows a preferred substance. A previous experiment indicated that contrast in consummatory behavior may also develop when a less preferred substance precedes a preferred substance in brief daily exposures. In the present experiment, the same animals sometimes received 0.15% saccharin followed, 15 sec later, by 32% sucrose (.15–32) and sometimes received 0.15% saccharin followed by the same 0.15% saccharin solution (.15-.15). One solution pair was given each day, and the two conditions, .15–32 and .15-.15, occurred in alternation across days. The two different solution conditions were correlated with different cues. Saccharin intake from the first tube was lower when the second tube contained 32% sucrose than when it contained .15% saccharin, both in original discrimination training and following a reversal of the cue-solution pairings. These results support the conclusion that contrast in this situation is based on the anticipation of the impending 32% sucrose each day, rather than on a retrograde comparison with the 32% sucrose received the previous day. These data are considered in terms of Pavlovian conditioning outcomes when the CS is a stimulus with hedonic value.     

Sociological analysis and comparative education: A brief bibliographical background

The bibliography cites English language material at the intersection of two fields of study: sociology of education and comparative education. The collection of material is biased (a) toward the general reader rather than the specialist already working in the area, and (b) toward the identification of overlap between the two fields of study.

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Zusammenfassung Diese Bibliographie umfaßt englischsprachiges Material am Schnittpunkt von zwei Studienfeldern: der Erziehungssoziologie und der Vergleichenden Erziehungswissenschaft. Das gesammelte Material ist (a) mehr auf den allgemeinen Leser als auf bereits in diesem Bereich tätige Wissenschaftler ausgerichtet, und (b) bezieht sich vorzugsweise auf die Feststellung von Überschneidungen zwischen den beiden Studiengebieten.

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Résumé La bibliographie cite le matériel en langue anglaise à l'intersection de deux domaines d'étude: la sociologie de l'éducation et l'éducation comparée. Le matériel rassemblé s'adresse davantage au lecteur ordinaire qu'au spécialiste travaillant déjà dans ce domaine et vise surtout l'identification de la partie commune aux deux champs d'étude.

     

Teacher labour markets in South Africa and Botswana: A comparative analysis

This article compares key features of the labour markets for teachers across Botswana and South Africa in order to seek possible explanations for the apparently larger teacher shortages in South Africa. It is argued that South African teachers earn relatively lower wages when compared to professionals with comparable qualifications; they have also been subject to a more haphazard series of reforms in teacher training, and are the product of a teaching culture shaped heavily by powerful trade unions. The impact of these factors on both the quantity and quality of teachers is considered.     

School knowledge and didactic analysis: A research perspective in comparative didactics

The article presents some aspects of an approach to disciplinary teaching phenomena that adopts the new perspective of comparative didactics. This approach consists of implementing research projects that examine teaching problems in a comparative study of various specific didactics.In the first part of the article, examination of the origins of school knowledge leads to the proposal of a new tool for analyzing the phenomena of didactic transposition in a broader perspective. In the second part, a new tool is proposed for analyzing in-class teaching phenomena for different disciplines.     

Behavioral field analysis in two strains of rats in a conditioned defensive burying paradigm

Two strains of rats (albino Wistar and hooded PVG/c) were exposed to a conditioned defensive burying paradigm that consisted of placing rats in a test chamber with bedding material on the floor, shocking them with a shock prod, and recording the time each rat spent in burying responses toward the prod. Various behaviors other than burying (freezing, grooming/paw licking) were observed by a time-sampling procedure during the control, conditioning, and extinction sessions, each of which was 15 min in duration. Wistar rats generally showed behavioral inhibition, as evidenced by less burying, lower exploratory and ambulatory behavior, and higher freezing behavior. PVG/c rats spent significantly more time engaged in burying and accumulated more bedding material in the conditioning session than did the Wistar rats. No significant differences between the two strains of rats were observed during the extinction session in terms of these measurements. The results indicate that Wistar rats have a greater tendency to freeze when coping with the noxious stimulus in a conditioned defensive burying paradigm, whereas the dominant coping style for PVG/c rats is defensive burying.     

Spatial memory and the performance of rats and pigeons in the radial-arm maze

The resource-distribution hypothesis states that the ability of an animal to remember the spatial location of past events is related to the typical distribution of food resources for the species. It appears to predict that Norway rats would perform better than domestic pigeons in tasks requiring spatial event memory. Pigeons, tested in an eight-arm radial maze, exhibited no more than half of the memory capacity observed in rats in the same apparatus and may not have used spatial memory at all. The results were interpreted as supporting the hypothesis.     

Ethnocentrism in education: A comparative analysis of problems in Eastern and Western Europe

Professor of modern Hungarian Literature at Budapest University, 1965/66 visiting Professor at the Sorbonne, Paris, 1981–88 Director General of the Hungarian National Institute of Pedagogy. Since 1989, responsible for educational and cultural research. Author of several books in his fields of competence.     

英汉语篇关联词对比研究

本文通过分析两者语言的特点,对比研究了英汉篇章中关联词的异同,旨在有助于外语教学中了解其相同及相异处,能够在关联词习得过程中有效利用其相同处,注意区分相异处,减少母语负迁移的产生。     

中德学前教育比较分析

对中德学前教育机构设置、课程设置、教学组织形式及学前学校教育与家庭教育的关系这四个方面进行比较的基础上,分析了造成中德学前教育差异的原因,结合德国学前教育的优点,对我国学前教育提出四条建议,以期为我国当前学前教育改革提供有益借鉴。