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.     

Species differences in temporal control of behavior

Temporal control of rats' and pigeons' responding was analyzed and compared in detail on fixed-interval and fixed-time schedules with parameters of 30, 60, and 120 seconds. On fixed-time schedules, rats' responding decreased greatly or ceased, whereas pigeons continued to respond, especially on low schedule values. The running rate of responses (calculated by excluding the postreinforcement pause) was related to the duration of the preceding postreinforcement pause for rats but not for pigeons. Changes in response rate in successive segments of the interval were best described by normal curves. The relationship between midpoints of the normal curves and schedule value was a power function, with an exponent of less than one for pigeons but greater than one for rats. These differences could be explained in terms of a basic difference between the key-peck and lever-press responses, the two being differently affected by the response-eliciting properties of food.     

Food and intracranial stimulation responding suppressed with regular-interval shock.

Attenuation of conditioned suppression during intracranial stimulation was compared with that during food reinforcement. Response rates controlled by food and by brain stimulation were equalized on a multiple schedule by adjusting the stimulating current. When foot shock was delivered during timeout periods separating response components, responding for food was significantly more suppressed than responding for brain stimulation. When components were shortened from 10 to 2 minutes, responding maintained by either food or brain stimulation showed a similar temporal pattern of suppression preceding each shock, but responding in the component involving food remained significantly more suppressed. Explanations for the attenuated suppression during brain stimulation based on neural disruption, stimulus blocking, and analgesic properties were questioned. The increased responding during brain stimulation seemed to reflect greater response strength relative to food reinforced responding.     

Psychophysics of key-peck duration in the pigeon

The duration of the pigeon's key peck was differentially reinforced in either a trials or a free-operant procedure. Mean emitted peck duration was a power function of the duration required for food delivery to occur. The exponents of the power function differed considerably from those observed in earlier research involving longer duration responses in pigeons and other species. The coefficients of variation also did not correspond with those of the earlier research on other responses, nor did consideration of the durations actually reinforced resolve the differences. Duration was neither a function of response rate nor of intermittency of reinforcement. Key-peck duration was changed in an orderly way by differential reinforcement. However, it appeared to be more strongly determined by its duration in the absence of differential reinforcement than were longer duration responses.     

Discriminative functions of schedule stimuli and memory: a combination of schedule and choice procedures

Pigeons responded under a combination brief-stimulus schedule and choice procedure. Normally, a fixed-interval schedule was in effect, where completion randomly produced either a brief stimulus or food. Intermittently, this schedule was interrupted by a choice arrangement. Two choice keys were lit, either a short or a long time since a prior event (food or stimulus). One choice response produced food if the time had been short, and the alternate response produced food if the time had been long. Across conditions, the duration of the fixed-interval schedule was varied, the stimuli that comprised the brief-stimulus operation were changed, and the stimuli were presented as paired and nonpaired with food. The focus of the study was the control of both schedule performance and choice responding across conditions. The results showed that choice accuracy was correlated with the degree of fixed-interval curvature, the response pattern of a pause followed by a gradually accelerated rate. As fixed-interval schedule duration was increased, both the degree of fixed-interval curvature and choice accuracy decreased. The particular brief stimulus used affected schedule and choice performance, with a more salient stimulus producing a greater degree of curvature and higher accuracy. Pairing and nonpairing operations produced striking differences in performance with the less salient brief stimulus, but not with the more salient stimulus. The results suggest that brief-stimulus schedule performance may be conceptualized in the context of memory research.     

《易经》的宇宙观与阴阳五行家思想之渊源

若从思想自身的发展来看,阴阳五行家与《易经》有着重要的渊源关系。《易经》的阴阳变化观念和带有浓厚的原始思维特性的宇宙观,是阴阳五行家思想的理论基石,阴阳五行家的宇宙发生图式和序列便滥觞于此。《易经》的以“因果联想”为重要特征的认知方式对阴阳五行家认识和把握世界的基本方式产生了重要的影响。《易经》的时空观念也与阴阳五行家以阴阳五行配四时、四方,以阴阳五行说明宇宙之大化、社会之变迁、人事之行止的思想紧密联系在一起。     

EFFECTS OF MORPHINE ON TEMPORAL DISCRIMINATION AND COLOR MATCHING: GENERAL DISRUPTION OF STIMULUS CONTROL OR SELECTIVE EFFECTS ON TIMING?

Discrepant effects of drugs on behavior maintained by temporal-discrimination procedures make conclusive statements about the neuropharmacological bases of timing difficult. The current experiment examined the possible contribution of a general, drug-induced disruption of stimulus control. Four pigeons responded on a three-component multiple schedule that included a fixed-interval 2-min, temporal discrimination, and color-matching component. Under control conditions, response rates and choice responses during the first two components showed evidence of control by time, and accuracy for color matching was high in the third component. Morphine administration flattened the distribution of fixed-interval responding and produced a general disruption of accuracy in the temporal-discrimination component, whereas accuracy in the color-matching component was relatively unaffected. Analysis of the psychophysical functions from the temporal-discrimination component indicated that morphine decreased accuracy of temporal discrimination by decreasing overall stimulus control, rather than by selectively affecting timing. These results suggest the importance of determining the neurophysiological bases of stimulus control as it relates to temporal discrimination.     

Giving Science a Bad Name: Politically and Commercially Motivated Fallacies in BSE Inquiry

It is a feature of scientific inquiry that it proceeds alongside a multitude of non-scientific interests. This statement is as true of the scientific inquiries of previous centuries, many of which brought scientists into conflict with institutionalised religious thinking, as it is true of the scientific inquiries of today, which are conducted increasingly within commercial and political contexts. However, while the fact of the coexistence of scientific and non-scientific interests has changed little over time, what has changed with time is the effect of this coexistence on scientific inquiry itself. While scientists may no longer construct their theories with various religious dictates in mind, growing commercial and political interests in science have served to distort the interpretation of science. Using the U.K.’s recent crisis with bovine spongiform encephalopathy (BSE) as my context, I examine two ways in which this distortion has occurred – the interpretation of the science of BSE by politicians and by commercial parties for the purposes of justifying policy decisions and informing the public of risk, respectively. Fallacious reasoning, I contend, is the manifestation of this distortion in these contexts. In demonstration of this claim, I examine how politicians and commercial parties alike have employed two fallacies in their assessments of the science of BSE. These fallacies extend in novel ways the set of so-called traditional informal fallacies. The interpretation of science, I conclude, is a rich context in which to conduct a study of fallacious reasoning; moreover, such a study can contribute in significant ways, I argue, to the public understanding of science.     

Mental rotation and temporal contingencies.

A task that requires subjects to determine whether two forms of the same shape, but in different orientations, are mirror images or identical except for orientation is called a handedness recognition task. Subjects' reaction times (RT) on this task are consistently related to the angular disparity (termed alpha) between the two presented forms. This pattern of data has been interpreted to indicate that subjects solve the task by imagining that one of the forms rotates into the orientation of the other (termed mental rotation). The speed with which one imagines one of the forms rotating has been widely considered a fixed capability of the individual, and thus immune to the effect of contingencies. We present an experiment that assesses the effects of temporal contingencies in a handedness recognition task on the slope of the function RT = f(alpha). The data indicate that the slope of this function can come under the control of temporal contingencies.     

There is no moral authority in medicine: response to Cowdin and Tuohey.

Central to the Cowdin-Tuohey paper is the concept of a moral authority proper to medical practitioners. Much as I agree with the authors in refusing to degrade doctors to the status of mere technicians, I argue that one does not succeed in retrieving the moral dimension of medical practice by investing doctors with moral authority. I show that none of the cases brought forth by Cowdin-Tuohey really amounts to a case of moral authority. Then I try to explain why no such cases can be found. Developing an insight that is common to all the major moral thinkers in the philosophia perennis, I show that doctors are professionally competent with respect only to a part of the human good; morally wise persons are competent with respect to that which makes man good as man. I try to show why it follows that a) professional expertise has no natural tendency to pass over into moral understanding, and that b) doctor and non-doctor alike start from the same point in developing their understanding of medical morality. It follows that the authors fail in their attempt to de-center the moral magisterium of the Church by setting up centers of moral authority outside of the Church.