Journal of the Experimental Analysis of Behavior

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Delay discounting as impaired valuation: Delayed rewards in an animal obesity model

Wed, 09/20/2017 - 03:22

Obesity is a major public health problem, which, like many forms of addiction, is associated with an elevated tendency to choose smaller immediate rather than larger delayed rewards, a response pattern often referred to as excessive delay discounting. Although some accounts of delay discounting conceptualize this process as impulsivity (placing the emphasis on overvaluing the smaller immediate reward), others have conceptualized delay discounting as an executive function (placing the emphasis on delayed rewards failing to retain their value). The present experiments used a popular animal model of obesity that has been shown to discount delayed rewards at elevated rates (i.e., obese Zucker rats) to test two predictions that conceptualize delay discounting as executive function. In the first experiment, acquisition of lever pressing with delayed rewards was compared in obese versus lean Zucker rats. Contrary to predictions based on delay discounting as executive function, obese Zucker rats learned to press the lever more quickly than controls. In the second experiment, progressive ratio breakpoints (a measure of reward efficacy) with delayed rewards were compared in obese versus lean Zucker rats. Contrary to the notion that obese rats fail to value delayed rewards, the obese Zucker rats' breakpoints were (at least) as high as those of the lean Zucker rats.

Categories: Academic Journals

The effects of fixed-interval schedules on variability of pigeons' pecking location

Wed, 09/20/2017 - 03:22

Many studies that have investigated performance under reinforcement schedules have measured response rate or interresponse time, which reflect the temporal dimension of responding; however, relatively few studies have examined other dimensions. The present study investigated the effects of fixed-interval schedules on the location of pigeons' pecking response. A circular response area 22.4 cm in diameter was used so that the pecking responses were effective over a wide range. Pigeons were exposed to a fixed-interval schedule whose requirement was systematically varied between conditions. Response location moved closer to the location of the last reinforced response as time elapsed in each trial. Additionally, as the fixed-interval duration requirement increased, response locations shifted to the border of the response area and the variability of response locations increased. These results suggest that fixed-interval schedules systematically control response location.

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Dogs don't always prefer their owners and can quickly form strong preferences for certain strangers over others.

Mon, 09/04/2017 - 06:10

The unique relationship between dog and owner has been demonstrated in several experimental procedures, including tests in which dogs are left alone or with a stranger, tests of dogs’ appeasement or social approach when petted by their owner or a stranger, and their ability to learn when taught by their owner or a stranger. In all cases, dogs responded differently to their owner, which has been referred to as a specific attachment, and likely a product of a prolonged history of reinforcement. In the current study, we used a concurrent choice paradigm in which dogs could interact with two people, both of whom provided the same petting interaction, to test whether owned dogs would prefer their owner over a stranger and whether the familiarity of the testing context would influence preference. We also investigated whether shelter and owned dogs tested with two strangers would show a preference between strangers and whether that preference would be similar in magnitude to any preference between the owner and stranger. Owned dogs preferred to interact with their owners when in an unfamiliar context, but allocated more time to the stranger in a familiar context. Both shelter and owned dogs tested with two strangers showed a magnitude of preference for one stranger over the other similar to owned dogs’ preference for owners in an unfamiliar context. These results parallel what has been found in strange situation tests with owned dogs tested with their owners, but the strength of preference shown for one of two strangers indicates dogs can form a preference for one person quickly.

Categories: Academic Journals

Reinforcement value and fixed-interval performance

Tue, 08/29/2017 - 03:42

The concept of reinforcement value summarizes the effect of different variables, such as reinforcement delay, reinforcement magnitude, and deprivation level, on behavior. In the present set of experiments, we evaluated the effect of reinforcement devaluation on performance under FI schedules. The literature on timing and reinforcement value suggests that devaluation generates longer expected times to reinforcement than the same intervals trained under control conditions. We devalued reinforcement with delay in Experiments 1A, 1B, and 2, and diminished deprivation in Experiments 3A and 3B. Devaluation reduced response rates, increased the number of one-response intervals, and lengthened postreinforcement pauses, but had inconsistent effects on other timing measures such as quarter life and breakpoint. The results of delayed reinforcement and diminished deprivation manipulations are well summarized as reinforcement devaluation effects. These results suggest that devaluation may reduce stimulus control. In addition, we argue that the process by which delayed reinforcement affects behavior might also explain some effects observed in other devaluation procedures through the concept of reinforcement value.

Categories: Academic Journals

Stimuli previously associated with reinforcement mitigate resurgence

Tue, 08/29/2017 - 03:41

Resurgence refers to the recurrence of an extinguished target behavior following subsequent suspension of alternative reinforcement. Delivery of reinforcers during extinction of alternative behavior has been shown to mitigate resurgence. The present experiment aimed to determine whether delivering stimuli associated with reinforcers during resurgence testing similarly mitigates resurgence. Three groups of rats pressed target levers for food according to variable-interval 15-s schedules during Phase 1. In Phase 2, lever pressing was extinguished, and an alternative nose-poke response produced alternative reinforcement according to a variable-interval 15-s schedule. Food reinforcement was always associated with illumination of the food aperture and an audible click from the pellet dispenser during Phases 1 and 2. Phase 3 treatments differed between groups. For one group, nose poking continued to produce food and food-correlated stimuli. Both of these consequences were suspended for a second group. Finally, nose poking produced food-correlated stimuli but not food for a third group. Target-lever pressing resurged in the group that received no consequences and in the group that received only food-correlated stimuli for nose poking. Resurgence, however, was smaller for the group that received food-correlated stimuli than for the group that received no consequences for nose poking. Target-lever pressing did not increase between phases in the group that continued to receive food and associated stimuli. Thus, delivery of stimuli associated with food reinforcement after suspension of food reduced but did not eliminate resurgence of extinguished lever pressing. These findings contribute to potential methodologies for preventing relapse of extinguished problem behavior in clinical settings.

Categories: Academic Journals

Training intraverbal bidirectional naming to establish generalized equivalence class performances

Tue, 08/29/2017 - 03:41

The purpose of this study was to evaluate the effects of tact and intraverbal training on the establishment of generalized equivalence classes. Seventeen college students were exposed to tact training, listener testing, and intraverbal training (A'B’ and B'C’) in two experiments. Visual–visual matching-to-sample and intraverbal tests measured performances consistent with the formation of equivalence classes. Generalization was assessed with four novel sets of stimuli. In the second experiment, matching-to-sample tests for baseline relations (AB, BC) were eliminated to control for the possibility that equivalence classes were developed through exposure to these visual stimulus–stimulus relations. Thirteen of 17 participants passed all matching-to-sample and intraverbal posttests. Results suggest that when trained and emergent intraverbal relations were not maintained or were faulty, participants did not respond correctly during matching-to-sample posttests.

Categories: Academic Journals

Response–reinforcer dependency and resistance to change

Thu, 08/17/2017 - 07:46

The effects of the response–reinforcer dependency on resistance to change were studied in three experiments with rats. In Experiment 1, lever pressing produced reinforcers at similar rates after variable interreinforcer intervals in each component of a two-component multiple schedule. Across conditions, in the fixed component, all reinforcers were response-dependent; in the alternative component, the percentage of response-dependent reinforcers was 100, 50 (i.e., 50% response-dependent and 50% response-independent) or 10% (i.e., 10% response-dependent and 90% response-independent). Resistance to extinction was greater in the alternative than in the fixed component when the dependency in the former was 10%, but was similar between components when this dependency was 100 or 50%. In Experiment 2, a three-component multiple schedule was used. The dependency was 100% in one component and 10% in the other two. The 10% components differed on how reinforcers were programmed. In one component, as in Experiment 1, a reinforcer had to be collected before the scheduling of other response-dependent or independent reinforcers. In the other component, response-dependent and -independent reinforcers were programmed by superimposing a variable-time schedule on an independent variable-interval schedule. Regardless of the procedure used to program the dependency, resistance to extinction was greater in the 10% components than in the 100% component. These results were replicated in Experiment 3 in which, instead of extinction, VT schedules replaced the baseline schedules in each multiple-schedule component during the test. We argue that the relative change in dependency from Baseline to Test, which is greater when baseline dependencies are high rather than low, could account for the differential resistance to change in the present experiments. The inconsistencies in results across the present and previous experiments suggest that the effects of dependency on resistance to change are not well understood. Additional systematic analyses are important to further understand the effects of the response–reinforcer relation on resistance to change and to the development of a more comprehensive theory of behavioral persistence.

Categories: Academic Journals

Are behaviors at one alternative in concurrent schedules independent of contingencies at the other alternative?

Mon, 08/14/2017 - 06:30

Some have reported changing the schedule at one alternative of a concurrent schedule changed responding at the other alternative (Catania, 1969), which seems odd because no contingencies were changed there. When concurrent schedules are programmed using two schedules, one associated with each alternative that operate continuously, changing the schedule at one alternative also changes the switch schedule at the other alternative. Thus, changes in responding at the constant alternative could be due to the change in the switch schedule. To assess this possibility, six rats were exposed to a series of conditions that alternated between pairs of interval schedules at both alternatives and a pair of interval schedules at one, constant, alternative and a pair of extinction schedules at the other alternative. Comparing run lengths, visit durations and response rates at the constant alternative in the alternating conditions did not show consistent increases and decreases when a strict criterion for changes was used. Using a less stringent definition (any change in mean values) showed changes. The stay/switch analysis suggests it may be inaccurate to apply behavioral contrast to procedures that change from concurrent variable-interval variable-interval schedules to concurrent variable-interval extinction schedules because the contingencies in neither alternative are constant.

Categories: Academic Journals

Searching for the variables that control human rule-governed “insensitivity”

Thu, 08/03/2017 - 22:55

Verbal rules or instructions often exert obvious and meaningful control over human behavior. Sometimes instructions benefit the individual by enabling faster acquisition of a skill or by obviating an aversive consequence. However, research has also suggested a clear disadvantage: “insensitivity” to changing underlying contingencies. The two experiments described here investigated the variables that control initial rule-following behavior and rule-following insensitivity. When the initial rule was inaccurate, behavior was consistent with the rule for approximately half of participants and all participants' behavior was mostly insensitive to changing contingencies. When the initial rule was accurate, behavior of all participants was consistent with it and behavior for nearly all participants was insensitive to changes in underlying contingencies. These findings have implications for how best to establish and maintain rule-following behavior in applied settings when deviant behavior would be more reinforcing to the individual.

Categories: Academic Journals

Generalization of the disruptive effects of alternative stimuli when combined with target stimuli in extinction

Thu, 08/03/2017 - 21:45

Differential-reinforcement treatments reduce target problem behavior in the short term but at the expense of making it more persistent long term. Basic and translational research based on behavioral momentum theory suggests that combining features of stimuli governing an alternative response with the stimuli governing target responding could make target responding less persistent. However, changes to the alternative stimulus context when combining alternative and target stimuli could diminish the effectiveness of the alternative stimulus in reducing target responding. In an animal model with pigeons, the present study reinforced responding in the presence of target and alternative stimuli. When combining the alternative and target stimuli during extinction, we altered the alternative stimulus through changes in line orientation. We found that (1) combining alternative and target stimuli in extinction more effectively decreased target responding than presenting the target stimulus on its own; (2) combining these stimuli was more effective in decreasing target responding trained with lower reinforcement rates; and (3) changing the alternative stimulus reduced its effectiveness when it was combined with the target stimulus. Therefore, changing alternative stimuli (e.g., therapist, clinical setting) during behavioral treatments that combine alternative and target stimuli could reduce the effectiveness of those treatments in disrupting problem behavior.

Categories: Academic Journals

Is talking to yourself thinking?

Thu, 08/03/2017 - 21:45

The question whether talking to yourself is thinking is considered from two viewpoints: radical behaviorism and teleological behaviorism. For radical behaviorism, following Skinner (1945), mental events such as ‘thinking’ may be explained in terms of private behavior occurring within the body, ordinarily unobservable by other people; thus, radical behaviorism may identify talking to yourself with thinking. However, to be consistent with its basic principles, radical behaviorism must hold that private behavior, hence thinking, is identical with covert muscular, speech movements (rather than proprioception of those movements). For teleological behaviorism, following Skinner (1938), all mental terms, including ‘thinking,’ stand for abstract, temporally extended patterns of overt behavior. Thus, for teleological behaviorism, talking to yourself, covert by definition, cannot be thinking.

Categories: Academic Journals

Choosing among multiple alternatives: Relative and overall reinforcer rates

Sun, 07/30/2017 - 23:55

Choice behavior among two alternatives has been widely researched, but fewer studies have examined the effect of multiple (more than two) alternatives on choice. Two experiments investigated whether changing the overall reinforcer rate affected preference among three and four concurrently scheduled alternatives. Experiment 1 trained six pigeons on concurrent schedules with three alternatives available simultaneously. These alternatives arranged reinforcers in a ratio of 9:3:1 with the configuration counterbalanced across pigeons. The overall rate of reinforcement was varied across conditions. Preference between the pair of keys arranging the 9:3 reinforcer ratio was less extreme than the pair arranging the 3:1 reinforcer ratio regardless of overall reinforcer rate. This difference was attributable to the richer alternative receiving fewer responses per reinforcer than the other alternatives. Experiment 2 trained pigeons on concurrent schedules with four alternatives available simultaneously. These alternatives arranged reinforcers in a ratio of 8:4:2:1, and the overall reinforcer rate was varied. Next, two of the alternatives were put into extinction and the random interval duration was changed from 60 s to 5 s. The ratio of absolute response rates was independent of interval length across all conditions. In both experiments, an analysis of sequences of visits following each reinforcer showed that the pigeons typically made their first response to the richer alternative irrespective of which alternative was just reinforced. Performance on these three- and four-alternative concurrent schedules is not easily extrapolated from corresponding research using two-alternative concurrent schedules.

Categories: Academic Journals

Control by past and present stimuli depends on the discriminated reinforcer differential

Sun, 07/23/2017 - 21:50

The extent to which a stimulus exerts control over behavior depends largely on its informativeness. However, when reinforcers have discriminative properties, they often exert less control over behavior than do other less reliable stimuli such as elapsed time. We investigated why less reliable cues in the present often overshadow stimulus control by more reliable cues presented in the recent past, by manipulating the reliability and duration of stimulus presentations. Five pigeons worked on a modified concurrent schedule in which the location of the response that produced the last reinforcer was a discriminative stimulus for the likely time and location of the next reinforcer. In some conditions, either the location of the previous reinforcer, or the location of the next reinforcer, was signaled by a red key light. This stimulus was either Brief, occurring for 10 s starting a fixed time after the most recent reinforcer, or Extended, being present at all times between food deliveries. Brief and Extended stimuli that signaled the same information had a similar effect on choice when they were present, but control by Brief stimuli weakened as time since stimulus offset elapsed. Control was divided among stimuli in the present and recent past according to the apparent reliability of the information signaled about the next reinforcer. More reliable stimuli in the present degraded, but did not erase, control by less reliable stimuli presented in the recent past. Thus, we conclude that less reliable stimuli in the present control behavior to a greater degree than do more reliable stimuli in the recent past because these more reliable stimuli are forgotten, and hence their relation to the likely availability of food cannot be discriminated.

Categories: Academic Journals

Aversive functions of response effort: Fact or artifact?

Wed, 07/12/2017 - 01:37

Historically, effort has been viewed as aversive. Most supporting evidence comes from studies demonstrating increased force/effort requirements reduce operant responding. Changes in force/effort requirements, however, are often accompanied by changes in response definition when mechanical devices are used to define the response. As a consequence, responses measured at one point in a study may go unmeasured at other points. In an alternative approach, we used a continuous measurement strategy that provided a means to fix the threshold force defining the response class and simultaneously allowed independent manipulation of the force criteria required to produce reinforcement. Rats pressed a force transducer according to a fixed-ratio 5 schedule of food delivery. The criterion force was systematically increased and decreased; the threshold for response detection was constant. When response rates included only criterion responses, overall rate decreased when force requirements increased. By contrast, when all responses, both those meeting force criteria and those that did not (above the threshold but below the criteria for reinforcement) were included in the rate calculation, increases in force increased response rate. Increases in force criteria also increased the maximum force (g) and time-integral of force (g-s) of operant behavior. Control conditions showed increases in responding could be explained by the emergence of subcriterion responses, irrespective of force. We conclude that prior results showing effort decreases response rates are due to an artifact arising from inadvertent changes in response definitions. Increases in effort may better be understood as changes in the response:reinforcer payoff owing to the emergence of a subcriterion response class.

Categories: Academic Journals

Discounting: A practical guide to multilevel analysis of indifference data

Wed, 07/12/2017 - 01:37

Multilevel modeling provides the ability to simultaneously evaluate the discounting of individuals and groups using indifference point data. After considering the conditions when weaknesses emerge in estimating individual discounting as a prelude to estimating group discounting, examples are provided that indicate that multilevel modeling improves estimation in the presence of variability and missing data, and when trying to fit two-parameter discounting functions. Concrete examples of how to fit nonlinear multilevel models are provided to help researchers in the adoption of these methods.

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Theoretical implications of quantitative properties of interval timing and probability estimation in mouse and rat

Mon, 06/26/2017 - 23:28

In three experiments with mice ( Mus musculus ) and rats (Rattus norvigicus), we used a switch paradigm to measure quantitative properties of the interval-timing mechanism. We found that: 1) Rodents adjusted the precision of their timed switches in response to changes in the interval between the short and long feed latencies (the temporal goalposts). 2) The variability in the timing of the switch response was reduced or unchanged in the face of large trial-to-trial random variability in the short and long feed latencies. 3) The adjustment in the distribution of switch latencies in response to changes in the relative frequency of short and long trials was sensitive to the asymmetry in the Kullback–Leibler divergence. The three results suggest that durations are represented with adjustable precision, that they are timed by multiple timers, and that there is a trial-by-trial (episodic) record of feed latencies in memory.

Categories: Academic Journals

Animal cognition + optimal choice = behavior: A review of adaptive behavior and learning, 2nd Ed., by J. E. R. Staddon

Mon, 06/26/2017 - 23:27

Staddon discusses a vast array of topics in comparative psychology in this book. His view is that adaptive behavior in most cases is the result of optimal choice acting on an animal's knowledge about the world. Staddon refers to this as a functional teleonomic approach inasmuch as it attempts to understand an animal's behavior in terms of goals. He builds mathematical models based on this idea that are designed to reproduce specific sets of empirical observations, usually qualitatively. A natural consequence of Staddon's approach is that many models are developed, each of which applies to a specific set of observations. An alternative to functional teleonomy is a functional approach that builds on prior principles. In most cases, this approach favors a single-theory account of behavior. Prior principles can be understood as functional stand-ins for antecedent material causes, which means that these accounts are closer to mechanistic theories than are goal-based teleonomic accounts. An ontological perspective, referred to as supervenient realism, is a means of understanding the relationship between functional theories and the material world. According to this perspective, the algorithmic operation of a successful functional theory may be understood to supervene on the material operation of the nervous system.

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A method for detailed movement pattern analysis of tadpole startle response

Mon, 06/26/2017 - 23:22

Prolonged space flight, specifically microgravity, presents a problem for space exploration. Animal models with altered connections of the vestibular ear, and thus altered gravity sensation, would allow the examination of the effects of microgravity and how various countermeasures can establish normal function. We describe an experimental apparatus to monitor the effects of ear manipulations to generate asymmetric gravity input on the tadpole escape response. To perform the movement pattern analysis, an imaging apparatus was developed that uses a high-speed camera to obtain time-resolved, high-resolution images of tadpole movements. Movements were recorded in a temperature-controlled test chamber following mechanical stimulation with a solenoid actuator, to elicit a C-start response. Temperature within the test cell was controlled with a recirculating water bath. Xenopus laevis embryos were obtained using a standard fertilization technique. Tadpole response to a controlled perturbation was recorded in unprecedented detail and the approach was validated by describing the distinct differences in response between normal and one-eared tadpoles. The experimental apparatus and methods form an important element of a rigorous investigation into the response of the tadpole vestibular system to mechanical and biochemical manipulations, and can ultimately contribute to improved understanding of the effects of altered gravity perception on humans.

Categories: Academic Journals