Potentiation by a taste of toxicosis-based context conditioning: Effects of varying the test fluid

Rats that drank water in a distinctive environment and were then injected with lithium chloride (water-lithium condition) were compared with those given an added taste on those conditioning sessions (sucrose-lithium condition). In three experiments this taste potentiated a conditioned aversion to the context, as measured by suppression of intake of another solution: either a novel sour taste (Experiments 1 and 2) or a familiar saline solution (Experiment 3). In contrast, this potentiation effect was not detected when subjects were tested with water, whether a high or low dose of lithium was used (Experiment 2). Instead, in Experiments 1 and 2 water-lithium subjects drank less water than did the sucrose-lithium subjects on such tests i.e. an apparent overshadowing effect, which was the opposite outcome to that found previously using almost identical procedures. Intake on recovery sessions in another context suggested that, when water is used as the test fluid, potentiation can be masked by two factors: a context-dependent aversion to water in water-lithium subjects, and a conditioned inhibition effect of water in sucrose-lithium subjects. These may account for previous failures to detect potentiation of context conditioning.     

The impact of Pavlov on the psychology of learning in English-speaking countries

The translation of Pavlov's lectures (Pavlov, 1927) provided English-speaking psychologists with access to the full scope of Pavlov's research and theoretical ideas. The impact this had on their study of the psychology of learning can be assessed by examining influential books in this area. This reveals that Watson (1924) had been highly effective in promoting the misleading idea that Pavlov was a fellow S-R theorist. This assumption was not questioned by Tolman (1932), Hilgard and Marquis (1940) or by Hull (1943). However, this mistake was not made by Skinner (1938), who also provided the strongest arguments against Pavlov's belief that behavioral effects required explanation in terms of physiological processes. Post-1927 most learning research in the English-speaking countries continued to use instrumental, rather than Pavlovian, conditioning procedures. Nevertheless, many of the issues addressed by this research were ones that Pavlov had been the first to raise, so that his major influence can be seen as that of defining a research program for subsequent students of learning.     

Varying temporal contiguity and interference in a human avoidance task

Temporal contiguity and number of interfering events were manipulated in a human avoidance (Martians) task, which required participants to prevent an "invasion" when a particular visual stimulus ("shield") appeared by releasing the space bar before the shield was activated. A particular symbol, 1 of up to 6, functioned as a brief warning signal. The signal-offset to shield-onset (S-S) interval varied between groups, as did the number of additional symbols acting as distractors. In Experiments 1 and 2, speed of learning declined as a linear function of both trace interval and number of distractors. Path analysis showed that the effects of the S-S interval depended primarily on the number of distractors during this interval. Experiment 2 further demonstrated that participants who failed to suppress responding were generally unable to identify which symbol was the signal, suggesting that the presence of distractors disrupted detection of the contingency rather than performance. Overall, the results indicated that learning to associate 2 temporally separated events depends mainly on the amount of interference and little on the time interval between them.     

Profile of Mood States Research in Sport and Exercise Psychology: Past,Present, and Future

Abstract

A review was conducted of the sport and exercise literature for the years 1971 to early 1998 in which the Profile of Mood States (POMS) figured prominently. Analyses indicated that there were 258 published articles in which the POMS was used with athletic or exercise samples during this time period. Of these articles, 226 were data-based and the remainder dealt with general, theoretical, or psychometric issues. Prominent journals publishing the data-based research, leading authors, sport samples used, gender issues, and temporal trends in the use of the POMS were noted. Anticipated future developments include: improvements in research methodologies used to study relationships among sport, exercise, and mood; continued validation of abbreviated forms of the scale as well as a form for use with youth samples; and increased utilization of the POMS for mood profiling.     

Activity-based anorexia: ambient temperature has been a neglected factor

Activity-based anorexia refers to the self-starvation of rats exposed to experimental conditions that combine restricted access to food with access to an activity wheel. This paper compares previous studies of this phenomenon in relation to the ambient temperatures (AT) that were employed. On this basis, and from some more direct evidence, we argue that AT is an important, but neglected, factor in activity-based anorexia research. More attention to AT is needed in future research, since its neglect threatens the validity of conclusions drawn from those studies. Furthermore, direct examination of the effect of AT on activity-based anorexia will allow a better understanding of the mechanisms underlying this phenomenon and the possible clinical implications for the treatment of human anorexia nervosa.     

Observing stimulus sources that signal food or no food

Pigeons were given a choice between observing a stimulus source that was uncorrelated with food or one that was informative. The informative source was either positive, in which a stimulus change signalled food, or negative, in which change signalled no food. If observing is supported by the reduction of uncertainty, the negative as well as the positive source should be preferred to the uncorrelated source. On the other hand, if observing requires support by conditioned reinforcement, the negative source should not be preferred to the uncorrelated source. Two keys served as stimulus sources in a discrete trial procedure. The keys were lighted together, remained on for a variable length of time, and went off together. A key could change color 1 sec before going off. In the uncorrelated source, the change occurred equally often on trials ending with or without food. In the positive information source, the change occurred only on food trials, whereas in the negative information source, it occurred only on no-food trials. All stimulus changes and food delivery were response independent. As measured by orientation and autoshaped pecking, the positive information source was preferred to the uncorrelated source. However, the uncorrelated source was preferred to the negative information source. The latter result does not support the view that observing behavior is reinforced by the reduction of uncertainty. The positive and negative information sources reduced uncertainty equally but only the positive source provided a signal that could act as a conditioned reinforcer by virtue of its relation to food.     

Short term retention of sentences

A series of experiments was performed on the interaction between the short-term retention of sentences and of digits. In Experiment I a digit span method was used whereby subjects were presented with a sentence followed by a sequence of digits and were required either (a) to recall the sentence first and then the digits or (b) to recall the digits followed by the sentence. Under condition (a) prior recall of the sentence reduced the percentage of digit sequences correctly recalled, while under condition (b) retention of the sentence appeared to have no effect on digit recall. This last finding was confirmed in Experiment II, where the sentences varied both in grammatical complexity and length.

In Experiment III the effect of prior recall of a sentence on the recall of digits was found to depend on the type of sentence used. A correlation was observed between the size of this effect and the time taken to recall a sentence. The rate of forgetting suggested by this observation was comparable to that obtained in Experiment IV, where subjects performed an intervening task that did not involve immediate memory for sentences in the interval between the presentation and recall of a six-digit sequence.

It was concluded from these results that the short-term retention of sentences and of lists of items cannot be explained in terms of some general store of limited capacity.     

Behavioral contrast and response independent reinforcement

Four pigeons received pre-training that included presentation of the reinforcer independently of behavior and then baseline training on a variable-interval schedule of reinforcement. With the introduction of a multiple schedule, in which the first stimulus was associated with a response contingent and a second stimulus with a response independent, 1-min variable-interval schedule, a reduction in response rate was obtained in the second component, which was not accompanied by a behavioral contrast effect in the first component. A further three pigeons were given the same pre-training and baseline training before the introduction of an otherwise identical multiple schedule, in which no reinforcement occured in the second component. Behavioral contrast was obtained from all three subjects. The results indicated that under conditions of constant reinforcement density a reduction in responding is not a sufficient condition for the occurrence of behavioral contrast.     

The development of a simple form of communication

This paper is concerned with situations in which one of two possible stimuli is presented to one subject, the sender, while a second subject is required to make one of two responses. The stimuli are not available to the receiver, but the latter can perceive the sender. Successful performance depends on the sender indicating what stimulus is present to the receiver. It is proposed that the development of this form of communication, initially observed with dolphins, can be understood in the light of recent autoshaping research. An experiment demonstrated that pairs of pigeons can learn to perform appropriately in such a situation and provided evidence supporting an autoshaping analysis.