The substitutability of reinforcers

Substitutability is a construct borrowed from microeconomics that describes a continuum of possible interactions among the reinforcers in a given situation. Highly substitutable reinforcers, which occupy one end of the continuum, are readily traded for each other due to their functional similarity. Complementary reinforcers, at the other end of the continuum, tend to be consumed jointly in fairly rigid proportion, and therefore cannot be traded for one another except to achieve that proportion. At the center of the continuum are reinforcers that are independent with respect to each other; consumption of one has no influence on consumption of another. Psychological research and analyses in terms of substitutability employ standard operant conditioning paradigms in which humans and nonhumans choose between alternative reinforcers. The range of reinforcer interactions found in these studies is more readily accommodated and predicted when behavior-analytic models of choice consider issues of substitutability. New insights are gained into such areas as eating and drinking, electrical brain stimulation, temporal separation of choice alternatives, behavior therapy, drug use, and addictions. Moreover, the generalized matching law (Baum, 1974) gains greater explanatory power and comprehensiveness when measures of substitutability are included.     

Category discrimination by pigeons using five polymorphous features

Eight pigeons were trained to discriminate between sets of color photographs of natural scenes. The scenes differed along five two-valued dimensions (site, weather, camera distance, camera orientation, and camera height), and all combinations of the feature values were used. One value of each dimension was designated as positive, and slides containing three or more positive feature values were members of the positive stimulus set. Thus, each feature had an equal, low, correlation with reinforcement, and all features had zero correlations with each other. Seven of the 8 pigeons learned this discrimination, and their responding came under the control of all five features. Within the positive and negative stimulus sets, response rates were higher to stimuli that contained more positive feature values. Once discrimination had been achieved, reversal training was given using a subset of the slides. In this subset, only a single feature was correlated with reinforcement. All pigeons learned this reversal successfully and generalized it to additional photographs with the same feature content. After reversal, the original reinforcement contingencies were reinstated, and training was continued using all the slides except those that had been used in reversal. Reversal generalized to these slides to some extent. Analysis of the response rates to individual slides showed that, compared with prereversal training, only the feature that had been subjected to reversal contingencies showed a reversed correlation with response rate. The remaining features showed the same correlation with response rate as they had before reversal training. Thus, reversal on some members of a category following category discrimination training led to generalization to stimuli within the category that were not involved in the reversal, but not to features that were not reversed. It is therefore inappropriate to refer to the pigeons as learning a concept.     

Harming future people

Hanser examines Derek Parfit's contention in his treatise on rationalism, Reasons and Persons (Oxford University Press; 1984) that acts that are not reproductive in nature can nonetheless predictably affect the identities of future people, and that this fact has unexpected and important consequences for ethical theory. Hanser argues tht this fact is not as significant as Parfit believes it to be. The arguments of both scholars concern the morality of choices that, while causing future persons to be badly off, do not make them worse off than they would have been if the choices had not been made. Hanser concludes his essay with a discussion of responsibility for acts that will affect the health of future offspring.     

Natural ways are better: Adolescents and the ‘anti-obesity’ gene

Empirical research with young people in Finland, Germany, Spain and Britain was carried out as part of the BIOCULT project funded by the European Union. The project focused on their attitudes to biotechnology and, in particular, the formation of arguments about risk and safety. This paper looks at the responses of 14–18 year olds to a story about the so called anti-obesity gene, in the form of advice to a friend who is taking it. The majority advised against taking it with some differences by gender and country. Most reservations were on grounds of safety and the feeling that ‘natural’ ways to lose weight are better: A minority questioned the idea of striving for a ‘perfect’ body. The types of arguments used by the young people reveal underlying perspectives on the place of human beings in the world and whether they have a right to manipulate nature and their own bodies. Marie Levitt is a sociologist with research interests in attitudes and values in relation to biotechnology, health and religion.     

环境伦理学

一、导论面对“环境危机”,环境哲学家们有一种相当普遍的共识,即应该从伦理学的角度来考察环境问题。他们一致认为,环境问题是重要的,但它在过去没有得到足够的重视。同样,他们也一致认为,在我们处理环境问题时,伦理学应起到更大的作用。然而,也有不一致的地方,即环境伦理学是由什么组成的,怎样才能实现它,在什么程度上实现它是理想的。本文考察当个环境伦理学的关键问题。价值观和对环境及为环境所采取的行动深深地被我们对环境的观察与理解影响着。因此,本文一开始叙述了在过去的一个世纪里,在环境问题上,科学对环境问题的…     

Evidence Supporting the Importance of Peripheral Visual Information for the Directional Control of Aiming Movement

The focus of the present study was on determining whether the high level of directional accuracy found in aiming studies in which the subjects can see their hand in the visual periphery supports the existence of a kinetic visual channel or, rather, the advantage of binocular over monocular vision for movement directional control. The limits of this kinetic visual channel were also explored. The results of the 1st experiment indicated that seeing one's hand in the visual periphery is sufficient to ensure optimal directional aiming accuracy. Further, no differences in aiming accuracy were noted between monocular and binocular vision. These results supported the existence of a visual kinetic channel. In the 2nd experiment, whether this kinetic visual channel would operate with movements slower (55 degrees /s) than those usually used in studies that had proved its existence (over 110 degrees /s) was delineated. The results indicated that this visual kinetic channel was operative even at relatively slow movement velocities. Central vision of the hand seemed to be used for on-line directional control of relatively slow movements.     

Gender Differences in Intercepting A Moving Target by Using a Throw or Button Press

Humans are a throwing species just as much as a talking species (Calvin, 1982), but preadaptations for throwing remain largely unexplored. The ability of undergraduate students (N = 165) to intercept a stimulus with a thrown object was determined for 10 stimulus speeds, ranging from 2 to 5 m/s. The inclusion of a condition in which the moving stimulus was intercepted. via button press allowed the role of the perceptual aspect of velocity estimation to be evaluated separately from the act of throwing. Gender differences were observed in both the button and the throwing intercept tasks: The men had smaller timing errors and higher accuracy than the women. Contrary to expectations, the male and female patterns of intercept errors as a function of stimulus speed were more similar in the throwing task than in the button intercept task     

Schedule interactions involving punishment with pigeons and humans

The principal aim of the present experiments was to assess whether punishment increased or decreased the rate of unpunished behavior (contrast and induction, respectively) for which reinforcement rate was held constant, with physical and nonphysical punishers (electric shock and response cost), pigeon and human subjects, signaled and unsignaled components (multiple and mixed schedules), and the presence or absence of a blackout period between components. Across the three experiments there were 20 punishment conditions. Induction was found in nine of those, less consistent response-rate reduction was found in three, contrast was found in four, and in four there was no change in responding from conditions without punishment. Contrast occurred consistently only with multiple schedules during the first exposure to electric-shock punishment. Induction and no change, however, were found with every combination of the independent variables studied. Four conclusions regarding the interactions between punished and unpunished responding emerged from the present results: (a) Both contrast and induction occurred with the reinforcement rate held constant and a blackout between components, (b) induction was more common than contrast, (c) contrast occurred only in the presence of a stimulus different from that correlated with the punisher, and (d) contrast diminished with prolonged exposure to punishment. None of the current theoretical accounts of punishment contrast can explain the present results.     

试答无法回答的问题

试答无法回答的问题让·多尔梅松著萧俊明译联合国教科文组织去年在巴黎以“我们不知道什么？”为主题召开了第一届哲学座谈会,取得了巨大的成功。《第欧根尼》第１６９期刊登了一些与会者的论文。第二届会议于１９９６年３月２７—３０日召开,讨论的问题如同前一届一样...