Effects of a DRL contingency added to a fixed-interval reinforcement schedule

Following 30 days of reinforcement for the bar press response of two white rats on 30-sec fixed-interval (FI), a DRL component was added so that a minimal interresponse time (IRT) for the reinforced response, in addition to the FI variable, was necessary for reinforcement. Marked control over response rate by the superimposed DRL requirement was demonstrated by an inverse hyperbolic function as the DRL component was increased from 1 to 24 sec within the constant 30-sec FI interval. Interresponse time and post-reinforcement (post-S^R) “break” distributions taken at one experimental point (DRL = 24 sec) suggested that a more precise temporal discrimination was initiated by an S^R than by a response, since the relative frequency of a sequence of two reinforced responses appeared greater than that of a sequence of a non-reinforced response followed by a reinforced one. This latter finding was confirmed with new animals in a follow-up experiment employing a conventional 24-sec DRL schedule.     

Competitive fixed-interval performance in humans

Two persons responded in the same session in separate cubicles, but under a single schedule of reinforcement. Each time reinforcement was programmed, only the first response to occur, that is, the response of only one of the subjects, was reinforced. “Competitive” behavior that developed under these conditions was examined in three experiments. In Experiment 1 subjects responded under fixed-interval (FI) 30-s, 60-s, and 90-s schedules of reinforcement. Under the competition condition, relative to baseline conditions, the response rates were higher and the pattern was “break-and-run.” In Experiment 2, subjects were exposed first to a conventional FI schedule and then to an FI competition schedule. Next, they were trained to respond under either a differential-reinforcement-of-low-rate (DRL) or fixed-ratio (FR) schedule, and finally, the initial FI competition condition was reinstated. In this second exposure to the FI competition procedure, DRL subjects responded at lower rates than were emitted during the initial exposure to that condition and FR subjects responded at higher rates. For all subjects, however, responding gradually returned to the break-and-run pattern that had occurred during the first FI competition condition. Experiment 3 assessed potential variables contributing to the effects of the competitive FI contingencies during Experiments 1 and 2. Subjects were exposed to FI schedules where (a) probability of reinforcement at completion of each fixed interval was varied, or (b) a limited hold was in effect for reinforcement. Only under the limited hold was responding similar to that observed in previous experiments.     

Inter-reinforcement times for the bar-pressing response of white rats on two DRL schedules,

A knowledge of inter-reinforcement times (IS^RT) seems of interest because, among other reasons, they bear on the variable of “reinforcement density” in behavior theory. IS^RT data were here recorded for bar-pressing responses by two white rats working on DRL 10 sec and DRL 40 sec. Sample inter-response time (IRT) distributions and cumulative records were taken simultaneously for comparison purposes. IS^RT sequences and distributions have certain characteristics that urge further investigation.     

Timing in free-operant and discrete-trial avoidance

A procedure (“discrete-trial” avoidance) was devised to differentiate between the two main theories of responding in Sidman's “free-operant” avoidance procedure. One theory, a version of two-factor theory, holds that responding is reinforced by the removal of a conditioned aversive stimulus. The conditioned aversive stimulus is held to be temporal, which accounts for the spaced responding, or timing, that Sidman's procedure produces. The other theory holds that the reinforcement for both responding and timing is shock-frequency reduction. The new procedure eliminated this reinforcement for timing, but retained the conditions for the formation of conditioned aversive temporal stimuli. According to one theory, the new procedure should have sustained timing as well as Sidman's, while according to the other, it should have sustained no timing. The results confirmed neither theory. Timing was found with both procedures, but unequally in degree and kind. Large variations in the precision of timing did not appear to be correlated with successful avoidance for either procedure.     

Repeated acquisition in the analysis of rule-governed behavior

Five children, ranging in age from 3½ years to 5½ years, were taught various four-response chains using conditioned reinforcement. Experiment 1 investigated the effects of presenting “instruction” stimuli—a sequence of lights over the correct response buttons—to assess their role in facilitating the acquisition of a chain of responses. Without the “instruction” stimuli, children made many errors before responses were brought under the control of the programmed contingencies. When confronted with the same contingencies later in the day, these subjects made fewer errors. In contrast, in the presence of the “instruction” stimuli, subjects made virtually no errors. However, when the “instruction” stimuli were discontinued in the subsequent session, all 5 subjects made errors. In Experiment 2, the subjects were taught to verbalize the contingencies during the phase without the “instruction” stimuli. This resulted in errorless performance during the subsequent exposure to the same procedure, but errors nevertheless occurred again during reexposure to the procedure with the “instruction” stimuli discontinued.     

Rule-governed behavior and sensitivity to changing consequences of responding

Humans were presented with a task that required moving a light through a matrix. Button presses could produce light movements according to a multiple fixed-ratio 18/differential-reinforcement-of-low-rate 6-s schedule, with components alternating every 2 min. Moving the light through the maze earned points worth chances on money prizes. In Experiment 1 four conditions were assessed through between-subject comparisons: minimal instructions, instructions to press rapidly, instructions to press slowly, and instructions that sometimes rapid responding would work while at other times a slow rate would work best. Subjects responded in three successive sessions of 32 min each. The results suggested that instructions affected the nature of the contact made with the programmed consequences and thus subsequent performance. In some cases, responding seemed to result from added contingencies introduced by stating rules. In Experiment 2 the relative contribution of these two effects was assessed by presenting and then withdrawing two lights that had been paired with two specific instructions: “Go Fast” or “Go Slow.” There were three conditions. In one condition, only the Go Fast light was on; in a second, only the Go Slow light was on; and in a third, the lights alternated each minute. In each condition, half the subjects had all instruction lights turned off after the first session. The results once again showed an effect of instructions on contact with the programmed consequences. However, responding sometimes continued in a manner consistent with added contingencies for rule-following even when the programmed consequences had been contacted and would have controlled a different type of responding in the absence of instructions. The relevance of added contingencies for rule-following in determining the effects of explicitly programmed consequences is emphasized.     

Bias in self-evaluation: Signal probability effects

Two experiments examined apparent signal probability effects in simple verbal self-reports. After each trial of a delayed matching-to-sample task, young adults pressed either a “yes” or a “no” button to answer a computer-presented query about whether the most recent choice met a point contingency requiring both speed and accuracy. A successful matching-to-sample choice served as the “signal” in a signal-detection analysis of self-reports. Difficulty of matching to sample, and thus signal probability, was manipulated via the number of nonmatching sample and comparison stimuli. In Experiment 1, subjects exhibited a bias (log b) for reporting matching-to-sample success when success was frequent, and no bias or a bias for reporting failure when success was infrequent. Contingencies involving equal conditional probabilities of point consequences for “I succeeded” and “I failed” reports had no systematic effect on this pattern. Experiment 2 found signal probability effects to be evident regardless of whether referent-response difficulty was manipulated in different conditions or within sessions. These findings indicate that apparent signal probability effects in self-report bias that were observed in previous studies probably were not an artifact of contingencies intended to improve self-report accuracy or of the means of manipulating signal probability. The findings support an analogy between simple self-reports and psychophysical judgments and bolster the conclusion of Critchfield (1993) that signal probability effects can influence simple self-reports much as they do reports about external stimuli in psychophysical experiments.     

Teaching serial position sequences to monkeys with a delayed matching-to-sample procedure

Comparison was made of two methods for training monkeys to “observe” a two-member serial position sequence by pressing two consecutively lighted keys and then to “report” the sequence by pressing the same two keys in the same order but without the lights. A fading technique involving gradual elimination of brightness cues from “reporting” keys was found more effective than a no-fading procedure in which the cues remained bright during training and then were suddenly removed. Animals that failed to learn to report a new sequence with the no-fading procedure sometimes developed behavior incompatible with that desired. They made repeated and specific errors that prematurely terminated trials of the sequence to-be-learned, even though the correct key was cued by a bright light. They behaved appropriately, however, on succeeding trials of other sequences. Thus, the errors were followed by trials on which reinforcement occurred. Manipulation of this contingency indicated its importance in maintaining the stereotyped error patterns.     

Olfactory learning in individually assayed Drosophila larvae

Insect and mammalian olfactory systems are strikingly similar. Therefore, Drosophila can be used as a simple model for olfaction and olfactory learning. The brain of adult Drosophila, however, is still complex. We therefore chose to work on the larva with its yet simpler but adult-like olfactory system and provide evidence for olfactory learning in individually assayed Drosophila larvae. We developed a differential conditioning paradigm in which odorants are paired with positive (“+” fructose) or negative (“-” quinine or sodium chloride) gustatory reinforcers. Test performance of individuals from two treatment conditions is compared—one received odorant A with the positive reinforcer and odorant B with a negative reinforcer (A+/B-); animals from the other treatment condition were trained reciprocally (A-/B+). During test, differences in choice between A and B of individuals having undergone either A+/B- or A-/B+ training therefore indicate associative learning. We provide such evidence for both combinations of reinforcers; this was replicable across repetitions, laboratories, and experimenters. We further show that breaks improve performance, in accord with basic principles of associative learning. The present individual assay will facilitate electrophysiological studies, which necessarily use individuals. As such approaches are established for the larval neuromuscular synapse, but not in adults, an individual larval learning paradigm will serve to link behavioral levels of analysis to synaptic physiology.     

Conditional discrimination and equivalence relations: A theoretical analysis of control by negative stimuli

A detailed analysis is presented of the ways in which control by the negative stimulus in two-comparison conditional discriminations may be expected to affect the outcome of tests for the properties of equivalence relations. Control by the negative stimulus should produce the following results: (a) no observable effect on symmetry tests; (b) reflexivity test results should look like “oddity” rather than “identity”; and (c) transitivity tests that involve an odd number of nodes should yield results that are 100% opposite to tests that involve an even number of nodes. The analysis also considers the effects of variation in the type of comparison-stimulus control between and within baseline conditional discriminations. Methods are suggested for experimentally regulating the type of control, and for verifying the predictions that the analysis generates. If suggested experiments continue to support the analysis, investigators who use two-comparison conditional discriminations to study equivalence relations will either have to control explicitly whether the positive or the negative comparison governs their subjects' choices, or they will have to abandon two comparisons and use three or more comparisons instead.     

The Meaning of Meaning-Fallibilism

Much discussion of meaning by philosophers over the last 300 years has been predicated on a Cartesian first-person authority (i.e. “infallibilism”) with respect to what one’s terms mean. However this has problems making sense of the way the meanings of scientific terms develop, an increase in scientific knowledge over and above scientists’ ability to quantify over new entities. Although a recent conspicuous embrace of rigid designation has broken up traditional meaning-infallibilism to some extent, this new dimension to the meaning of terms such as “water” is yet to receive a principled epistemological undergirding (beyond the deliverances of “intuition” with respect to certain somewhat unusual possible worlds). Charles Peirce’s distinctive, naturalistic philosophy of language is mined to provide a more thoroughly fallibilist, and thus more realist, approach to meaning, with the requisite epistemology. Both his pragmatism and his triadic account of representation, it is argued, produce an original approach to meaning, analysing it in processual rather than objectual terms, and opening a distinction between “meaning for us”, the meaning a term has at any given time for any given community and “meaning simpliciter”. the way use of a given term develops over time (often due to a posteriori input from the world which is unable to be anticipated in advance). This account provocatively undermines a certain distinction between “semantics” and “ontology” which is often taken for granted in discussions of realism.     

Stimulus timing by people with Parkinson's disease

Previous literature suggests that Parkinson’s disease is marked by deficits in timed behaviour. However, the majority of studies of central timing mechanisms in patients with Parkinson’s disease have used timing tasks with a motor component. Since the motor abnormalities are a defining feature of the condition, the status of timing in Parkinson’s disease remains uncertain. Data are reported from patients with mild to moderate Parkinson’s disease (both on and off medication) and age- and IQ-matched controls on a range of stimulus timing tasks without counting. Tasks used were temporal generalization, bisection, threshold determination, verbal estimation, and a memory for duration task. Performance of patients was generally “normal” on all tasks, but significant differences from performance of controls were found on the memory for duration task. Among the “normal” effects noted were arithmetic mean bisection, asymmetric temporal generalization gradients, and subjective shortening on the memory for duration task. The results suggest (a) that some previous reports of timing “deficits” in Parkinson’s patients were possibly due to the use of tasks requiring a timed manual response and (b) small differences between patients and controls may be found on tasks where two stimuli are presented on each trial, whether patients are on medication or off it.     

When History Seems to Repeat Itself: Exposure to Perceived Lessons of the Past Influences Predictions About Current Political Events

The idea that the past holds lessons for the present, under the guise of historical analogies, is prevalent in political and public discourse. Those analogies are often accompanied by dire warnings befalling those who “forget” or otherwise neglect the powerful lessons of History—and would then be “doomed to repeat it”, as the saying goes. So, Would remembering history make it seem more OR LESS likely to repeat itself in the future? In other words, does exposure to specific lessons about past events, especially ones involving causal claims, affect how people expect real-life events to turn out? Four studies (three preregistered) tested this experimentally. In Studies 1 and 2, participants expected the same behavior (the US adopting a harsh stance against Iran in the Nuclear Treaty) to result in a more negative outcome when this current stance seemed to match a “lesson” they had read about the break-out of World War II (European leaders adopting a harsh approach against Germany in the 1919 Versailles Treaty vs. a conciliatory approach in the 1938 Munich Agreement). Studies 3 and 4 attempted to eliminate some confounds present in the first two studies and to generalize the effect to different events. While results varied across studies, an internal meta-analysis indicated that the analogical effect on predictions (d = –.08) tended to become stronger as participants’ knowledge about the target situation decreased (d-1SD = –.24). These findings support the possibility of analogical-based predictive effects for real-life political events, and are discussed in light of their research and political implications.     

Development of a complex multiple schedule in the chimpanzee

The development of chimpanzee behavior on a four-component, three-lever multiple schedule is described. Component schedules included the Sidman avoidance procedure with a concurrent discriminated avoidance schedule on a second lever, fixed ratio performance for food, differential reinforcement of low rate for water requiring a dual response chain, and a symbol discrimination task for continuous food reinforcement using three levers. The avoidance component of this schedule was employed during the January 31, 1961 suborbital space flight of the chimpanzee “Ham.” On November 29, 1961, the chimpanzee “Enos” performed on the multiple schedule during three orbits around the earth in a Mercury capsule.     

Conditional discrimination learning: A critique and amplification

Carter and Werner recently reviewed the literature on conditional discrimination learning by pigeons, which consists of studies of matching-to-sample and oddity-from-sample. They also discussed three models of such learning: the “multiple-rule” model (learning of stimulus-specific relations), the “configuration” model, and the “single-rule” model (concept learning). Although their treatment of the multiple-rule model, which seems most applicable to the pigeon data, is generally excellent, their discussion of the other two models is incomplete and sometimes inaccurate. Potential problems of terminology are discussed in the present paper, as are additional lines of research that deserve consideration by those interested in further work in this area. The issue of response versus stimulus selection (configuration versus compound-cue learning) is discussed in connection with the configuration model. Particular attention is given to Carter and Werner's criticism of the application, in studies with other species, of the learning set procedure in testing for single-rule learning. Some of the important related issues are: the bias for improvement on new problems in a series, the adequacy of a multiple-rule model to explain learning set formation, and evidence in favor of the single-rule model, at least in primates. Consideration of these additional contributions to the study of conditional discrimination learning emphasizes the usefulness of this task in the comparative study of cognitive processes.     

Prepositional phrases spoken and heard

The relation between verbal and nonverbal behavior with common syntactic properties was investigated, using retarded and nonretarded children. Reinforcement was contingent on either verbal or nonverbal responses whereas responses of the other repertoire had no experimental consequences. Changes sometimes occurred in the unreinforced (collateral) repertoire, but they were always changes in the stimulus control of pre-existing topographies. A contingency involving responses of one repertoire never instated new topographies in the collateral repertoire. This suggested that the problem of “cross-modality generalization” should be reformulated to distinguish explicitly between instating new topographies and changing the stimulus control of pre-existing topographies. The result confirmed Skinner's hypothesis about “the same response spoken and heard” and clarified some anomalies in previous studies.     

The associative relation underlying autoshaping in the pigeon

Fifteen pigeons were exposed to either response-independent or response-dependent schedules of water reinforcement, whereby water was injected directly into the unrestrained pigeons' mandibles. Key-contact responses were released by a lighted key correlated with water, but not by a lighted key uncorrelated with water. A negative response-reinforcer contingency suppressed autoshaped key-contact responses, resulting in responding directed away from the lighted key. In all pigeons, water injected directly into the mandibles elicited a consummatory fixed-action pattern of “mumbling” and swallowing. The lighted key correlated with water released a broader set of both appetitive and consummatory responses: approach to the lighted key, “bowing”, “rooting”, “mumbling”, and swallowing. Key-contact responses were “rooting” and “mumbling” motions of the beak on the surface of the key. Views of autoshaping based on stimulus substitution or stimulus surrogation do not fully explain the origin of autoshaped responses not previously elicited by the reinforcer. The present findings are consonant with views of conditioning that emphasize the large degree of biological pre-organization in conditioned response patterns, and the importance of associative factors in the control of such patterns.     

Commentary on Malone: Who Founded Behaviorism?

Malone (The Behavior Analyst, 37, 1–12 2014) argued that the emergence of behaviorism was inevitable with or without Watson’s participation, mainly because protobehavioral ideas and dissatisfaction with classical structuralism were already widespread. However, the first premise is questionable because many of the ideas Malone cited were consistent with structuralism rather than behaviorism, and even if both premises were true they would not make the emergence of behaviorism—or anything else—inevitable. Historical evidence for inevitability is always retrospective and therefore always allows the logical fallacy of “after this, therefore because of this.” In the relevant real world Watson existed, he was a psychologist, he was the first to publish an article that described a “behaviorism,” and he promoted his behaviorism in later works. Stories about what would have happened without Watson’s participation are therefore counterfactual and this lack of historicity makes the stories fictional rather than scientific. In the real world, Watson founded behaviorism.     

Recognition by the pigeon of stimuli varying in two dimensions

Pigeons served in four experiments, each of which involved about 44,000 discrete 1.2-sec trials under steady-state conditions. The first experiment scaled a short segment of the visual wavelength continuum; this dimension was then combined in a conditional discrimination with each of three others; time after reinforcement, tone frequency, and line tilt. In the two-stimulus experiments, the birds' responses were reinforced in the presence of only one stimulus combination: “582 nm” together with “2 min after reinforcement”, “3990 Hz”, or “vertical line”. Many other stimulus combinations also appeared equally often and went without reinforcement. The wavelength stimuli conformed to an equal-interval scale, and per cent response was generally linear with wavelength, when scaled on cumulative normal coordinates. The components of the compound stimulus were found to interact in a multiplicative fashion; when one component differed greatly from its reinforcement value, changes in the other component had relatively little effect. For the “time”-“wavelength” compound, this interaction appeared to be modified by the effects of set or attention. Certain response latency data are reported, and other combination rules are discussed.