Rat AA-26: behavioral pharmacology science pioneer.

Rat AA-26, despite 1950s "state of the art," nonetheless generated the first set of behavioral pharmacology cumulative records to appear in the weekly journal Science, the century-old publication of the American Association for the Advancement of Science. The laboratory exploits of this dedicated animal called early attention to the methodological fruits of a marriage between pharmacology and the experimental analysis of behavior.     

Testing the reinforcing properties of S-: a replication of Lieberman''s procedure

A critical issue in testing theories of observing is whether the stimulus associated with extinction (the S-) reinforces observing responses. In previous experiments, subjects have been trained to make observing responses that produce both the S- and the stimulus correlated with reinforcement (the S+). Then, either the S+ or the S- has been withheld. Conflicting results have been attributed to differences among species. In the present experiments, pecking one key by master pigeons was reinforced with grain on a variable-ratio extinction schedule. Yoked pigeons received the grain on a variable-interval, extinction schedule controlled by the variable-ratio performances of the master birds. For both groups, concurrent pecking on a second key was reinforced on a variable-interval schedule with displays of discriminative stimuli. Subsequently, either the S+ or the S- was eliminated from the procedure. Omission of S+ produced a large decrease, as predicted by traditional conditioned reinforcement accounts of observing. By itself, S- did not maintain observing. A smaller and less reliable decrease, comparable to that obtained by Lieberman (1972) with rhesus monkeys, occurred when S- was eliminated. This replication with pigeons of Lieberman's results indicates that they are not species-specific, and the fact that observing was not maintained by S- alone suggests that the decrease obtained when S- was omitted is not attributable to the reinforcing power of S-.     

Choice for conditioned reinforcers in the signaled absence of primary reinforcement

Pigeons responded in a multiple schedule in which concurrent schedules of brief-stimulus presentation alternated with a component in which food was available (concurrent-chains component). In the initial links of the concurrent-chains component subjects chose either of two stimuli each correlated with the terminal link of one chain. The terminal links involved either variable-interval 30-second or variable-interval 60-second schedules. In the brief-stimulus component subjects chose between 0.5-second presentations of the terminal-link stimuli from the concurrent-chains component. Responding was generally maintained in the brief-stimulus component in two subjects for more than 300 sessions, suggesting that brief stimuli were conditioned reinforcers. During the brief-stimulus component, in 17 of 21 cases for which a minimal number of responses occurred, choice proportions above 0.55 were obtained for the brief-stimulus presentations correlated with the higher rate of primary reinforcement in the concurrent-chains component. These results support the suggestion that choice in conventional concurrent-chains procedures is partially controlled by production of the terminal-link stimuli.     

Enhancement of conditioned autonomic responses in monkey when preshock signals occasion operant suppression.

Classical pairings of a sound stilulus with shock elicited larger magnitude and more rapidly conditioned autonomic responses when subjects were responding on variable-interval schedules for food than when they were eating freely available food. The difference was not attributable to changes in control values of heart rate and blood pressure, or to alterations in motor activity, but appeared related to operant suppression.     

Choice and number of reinforcers

Pigeons were exposed to the concurrent-chains procedure in two experiments designed to investigate the effects of unequal numbers of reinforcers on choice. In Experiment 1, the pigeons were indifferent between long and short durations of access to variable-interval schedules of equal reinforcement density, but preferred a short high-density terminal link over a longer, lower density terminal link, even though in both sets of comparisons there were many more reinforcers per cycle in the longer terminal link. In Experiment 2, the pigeons preferred five reinforcers, the first of which was available after 30 sec, over a single reinforcer available at 30 sec, but only when the local interval between successive reinforcers was short. The pigeons were indifferent when this local interval was sufficiently long. The pigeons' behavior appeared to be under the control of local terminal-link variables, such as the intervals to the first reinforcer and between successive reinforcers, and was not well described in terms of transformed delays of reinforcement or reductions in average delay to reinforcement.     

Within-session changes in key and lever pressing for water during several multiple variable-interval schedules

Rats pressed keys or levers for water reinforcers delivered by several multiple variable-interval schedules. The programmed rate of reinforcement varied from 15 to 240 reinforcers per hour in different conditions. Responding usually increased and then decreased within experimental sessions. As for food reinforcers, the within-session changes in both lever and key pressing were smaller, peaked later, and were more symmetrical around the middle of the session for lower than for higher rates of reinforcement. When schedules provided high rates of reinforcement, some quantitative differences appeared in the within-session changes for lever and key pressing and for food and water. These results imply that basically similar factors produce within-session changes in responding for lever and key pressing and for food and water. The nature of the reinforcer and the choice of response can also influence the quantitative properties of within-session changes at high rates of reinforcement. Finally, the results show that the application of Herrnstein's (1970) equation to rates of responding averaged over the session requires careful consideration.     

Context effects on choice.

Four pigeons responded on a concurrent-chains schedule in four experiments that examined whether the effectiveness of a stimulus as a conditioned reinforcer is best described by a global approach, as measured by the average interreinforcement interval, or by a local contextual approach, as measured by the onset of the stimulus preceding the conditioned reinforcer. The interreinforcement interval was manipulated by the inclusion of an intertrial interval, which increased the overall time to reinforcement but did not change the local contingencies on a given trial A global analysis predicted choice for the richer alternative to decrease with the inclusion of an intertrial interval, whereas a local analysis predicted no change in preference. Experiment 1 examined sensitivity to intertrial intervals when each was signaled by the same houselight that operated throughout the session. In Experiment 2, the intertrial interval always was signaled by the stimulus correlated with the richer terminal link. In Experiment 3, the intertrial interval was signaled by the keylights correlated with the initial links and two novel houselights. Experiment 4 provided free food pseudorandomly during the intertrial interval. In all experiments, subjects' preferences were consistent with a local analysis of choice in concurrent chains. These results are discussed in terms of delay-reduction theory, which traditionally has failed to distinguish global and local contexts.     

预期错误与急性应激对不同强度恐惧记忆提取消退的影响

在条件性恐惧记忆再巩固模型下, 预期错误被证明是引发记忆不稳定的必要条件, 但其在不同强度恐惧记忆下的作用尚不明确。对于高强度可能导致的提取无效, 缺乏相应的探索以寻找解决办法, 而应激(stress)在其中发挥的作用值得探索。本研究考察人类被试中, 预期错误在不同强度恐惧记忆下的作用, 以及提取之后施加外源性应激对于消退进程的影响。结果发现, 对于较弱的恐惧记忆, 单个预期错误提取后消退可显著抑制恐惧自发恢复; 而对于较强恐惧记忆, 单个预期错误不能提取恐惧记忆进入再巩固, 已消退的记忆还会复发; 且在该种情况下, 如果在提取后施加外源性急性应激, 会进一步增大恐惧恢复。     

Punishment and its putative fallout: A reappraisal

In his book Coercion and Its Fallout Murray Sidman argued against the use of punishment based on concerns about its shortcomings and side effects. Among his concerns were the temporary nature of response suppression produced by punishment, the dangers of conditioned punishment, increases in escape and avoidance responses, punishment-induced aggression, and the development of countercontrol. This paper revisits Sidman's arguments about these putative shortcomings and side effects by examining the available data. Although Sidman's concerns are reasonable and should be considered when using any form of behavioral control, there appears to be a lack of strong empirical support for the notion that these potential problems with punishment are necessarily ubiquitous, long-lasting, or specific to punishment. We describe the need for additional research on punishment in general, and especially on its putative shortcomings and side effects. We also suggest the need for more effective formal theories of punishment that provide a principled account of how, why, and when lasting effects of punishment and its potential side effects might be expected to occur or not. In addition to being necessary for a complete account of behavior, such data and theories might contribute to improved interventions for problems of human concern.     

A low‐cost platform for eye‐tracking research: Using Pupil© in behavior analysis

Tracking eye movements is being increasingly recognized as a valuable source of information about stimulus control. So far, however, eye‐tracking research has suffered from accessibility issues, with expensive hardware and closed‐source software. In this article we review Pupil©, an eye‐tracking platform developed by Pupil Labs and that combines open‐source software with low‐cost hardware components. We offer concrete recommendations about Pupil use in stimulus‐control research and we show how the software can be extended to automatize the analysis of gaze data. Finally, we present the results of a study of visual discrimination and conditioned reinforcement conducted with Pupil, establishing the usefulness of this platform as a research tool in behavior analysis.