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Abstract Most investigations of briefly delayed reinforcement have involved schedules that arrange a time‐plus‐response requirement. The present experiment examined whether briefly delaying reinforcement on schedules that have a ratio requirement differs from results with schedules that have a time‐plus‐response requirement. Four pigeons responded on a two‐component multiple schedule. One component arranged a variable‐ratio (VR) 50 and the other a variable‐interval (VI) schedule in which the distribution of reinforcers was yoked to the preceding VR schedule. Across a series of conditions, delays were imposed in both schedules. These delays were brief (0.25‐ or 0.5‐s) unsignaled delays and, as control conditions, a 5‐s unsignaled delay and a 0.5‐s delay signaled by a blackout of the chamber. In the yoked‐VI component, the brief unsignaled delay increased response rates in six of nine opportunities and increased the proportion of short interresponse times (IRTs) (<0.4 s) in eight of nine opportunities. In the VR component, the brief unsignaled delay increased response rates and the proportion of short IRTs in only two of nine opportunities. For two of the three pigeons that were exposed to the 5‐s unsignaled delay, response rates and the proportion of short IRTs decreased in both of the components. The 0.5‐s signaled delay did not systematically change response rates nor did it change the distribution of short IRTs relative to the immediate reinforcement condition. The results replicate effects reported with time‐based schedules and extend these observations by showing that changes commonly observed in VI performance with briefly delayed reinforcement are not characteristic of VR responding.

Abstract A complex system is one that generates emergent structures, usually by the repeated application of relatively simple rules. The structures are emergent in the sense that they are not specified in, and cannot be predicted from, the rules that produce them. Mitchell argues for a unified science of complexity but does not ultimately succeed in providing a coherent account. Her book is nevertheless useful as an introduction to some systems and algorithms that have been studied in complexity research and that may be applicable to natural phenomena, including the behavior of organisms. The book also contains interesting historical and biographical details about complexity research and some of the mathematicians and scientists who have contributed to it. A sample of the specific complex systems and algorithms Mitchell introduces is examined in this review, including iterated maps, cellular automata, genetic algorithms, and small world and random Boolean networks. The relevance of complexity theory for behavior analysis is also considered, including applications of simple rules, networks, cellular automata, and genetic algorithms.

Abstract Foundational studies in decision making focused on behavior as the most accessible and reliable data on which to build theories of choice. More recent work, however, has incorporated neural data to provide insights unavailable from behavior alone. Among other contributions, these studies have validated reinforcement learning models by demonstrating neural signals posited on the basis of behavioral work in classical and operant conditioning. In such models, the values of actions or options are updated incrementally based on the difference between expectations and outcomes, resulting in the gradual acquisition of stable behavior. By contrast, natural environments are often dynamic, including sudden, unsignaled shifts in reinforcement contingencies. Such rapid changes may necessitate frequent shifts in behavioral mode, requiring dynamic sensitivity to environmental changes. Recently, we proposed a model in which cingulate cortex plays a key role in detecting behaviorally relevant environmental changes and facilitating the update of multiple behavioral strategies. Here, we connect this framework to a model developed to handle the analogous problem in motor control. We offer a tentative dictionary of control signals in terms of brain structures and highlight key differences between motor and decision systems that may be important in evaluating the model.

Abstract Excessively devaluing delayed reinforcers co‐occurs with a wide variety of clinical conditions such as drug dependence, obesity, and excessive gambling. If excessive delay discounting is a trans‐disease process that underlies the choice behavior leading to these and other negative health conditions, efforts to change an individual's discount rate are arguably important. Although discount rate is often regarded as a relatively stable trait, descriptions of interventions and environmental manipulations that successfully alter discount rate have begun to appear in the literature. In this review, we compare published examples of procedures that change discount rate and classify them into categories of procedures, including therapeutic interventions, direct manipulation of the executive decision‐making system, framing effects, physiological state effects, and acute drug effects. These changes in discount rate are interpreted from the perspective of the competing neurobehavioral decision systems theory, which describes a combination of neurological and behavioral processes that account for delay discounting. We also suggest future directions that researchers could take to identify the mechanistic processes that allow for changes in discount rate and to test whether the competing neurobehavioral decision systems view of delay discounting is correct.

Abstract We have adapted a nonhuman primate model of cocaine versus food choice to the rat species. To evaluate the procedure, we tested cocaine versus food choice under a variety of environmental manipulations as well as pharmacological pretreatments. Complete cocaine‐choice dose‐effect curves (0–1.0 mg/kg/infusion) were obtained for each condition under concurrent fixed ratio schedules of reinforcement. Percentage of responding emitted on the cocaine‐reinforced lever was not affected significantly by removal of cocaine‐associated visual or auditory cues, but it was decreased after removal of response‐contingent or response‐independent cocaine infusions. Cocaine choice was sensitive to the magnitude and fixed ratio requirement of both the cocaine and food reinforcers. We also tested the effects of acute (0.32, 0.56, 1.0, 1.8 mg/kg) and chronic (0.1, 0.32 mg/kg/hr) d‐amphetamine treatment on cocaine choice. Acute and chronic d‐amphetamine had opposite effects, with acute increasing and chronic decreasing cocaine choice, similar to observations in humans and in nonhuman primates. The results suggest feasibility and utility of the choice procedure in rats and support its comparability to similar procedures used in humans and monkeys.

Abstract Key pecking of 4 pigeons was studied under a two‐component multiple schedule in which food deliveries were arranged according to a fixed and a variable interfood interval. The percentage of response‐dependent food in each component was varied, first in ascending (0, 10, 30, 70 and 100%) and then in descending orders, in successive conditions. The change in response rates was positively related to the percentage of response‐dependent food in each schedule component. Across conditions, positively accelerated and linear patterns of responding occurred consistently in the fixed and variable components, respectively. These results suggest that the response–food dependency determines response rates in periodic and aperiodic schedules, and that the temporal distribution of food determines response patterns independently of the response–food dependency. Running rates, but not postfood pauses, also were positively related to the percentage of dependent food in each condition, in both fixed and variable components. Thus, the relation between overall response rate and the percentage of dependent food was mediated by responding that occurred after postfood pausing. The findings together extend previous studies wherein the dependency was either always present or absent, and increase the generality of the effects of variations in the response–food dependency from aperiodic to periodic schedules.

Abstract Two alternative approaches describe determinants of responding to a stimulus temporally distant from primary reinforcement. One emphasizes the temporal relation of each stimulus to the primary reinforcer, with relative proximity of the stimulus determining response rate. A contrasting view emphasizes immediate consequences of responding to the stimulus, the key factor being the conditioned reinforcement value of those immediate consequences. To contrast these approaches, 4 pigeons were exposed to a two‐component multiple schedule with three‐link chain schedules in each component. Only middle‐link stimuli differed between chains. Baseline reinforcement probabilities were 0.50 for both chains; during discrimination phases it was 1.0 for one chain and 0.0 for the other. During discrimination phases pigeons responded more to the reinforcement‐correlated middle link than to the extinction‐correlated middle link, demonstrating that responding was affected by the probability change. Terminal link responding was also higher in the reinforced chain, even though the terminal link stimulus was identical in both chains. Of greatest interest is initial link responding, which was temporally most distant from reinforcement. Initial link responding, necessarily equal in the two chains, was significantly higher during the 1.0/0.0 discrimination phases, even though overall reinforcement probability remained constant. For 3 of 4 birds, in fact, initial‐link response rates were higher than terminal‐link response rates, an outcome that can be ascribed only to the potent conditioned reinforcement properties of the middle‐link stimulus during the discrimination phases. Results are incompatible with any account of chain behavior based solely on relative time to reinforcement.

Abstract Behavior consultants conducted functional analyses (FAs) via telehealth with 20 young children with autism spectrum disorders between the ages of 29 and 80 months who displayed problem behavior and lived an average of 222 miles from the tertiary hospital that housed the behavior consultants. Participants' parents conducted all procedures during weekly telehealth consultations in regional clinics located an average of 15 miles from the participants' homes. Behavior consultants briefly trained parent assistants to provide on‐site support for families during consultations. FAs completed within a multielement design identified environmental variables that maintained problem behavior for 18 of the 20 cases, and interrater agreement averaged over 90%. Results suggested that behavior analysts can conduct FAs effectively and efficiently via telehealth.

Under intermittent food schedules animals develop temporally organized behaviors throughout interfood intervals, with behaviors early in the intervals (interim) normally occurring in excess. Schedule‐induced drinking (a prototype of interim, adjunctive behavior) is related to food deprivation and food frequency. This study investigated the interactions that resulted from combining different food‐deprivation levels (70%, 80% or 90% free‐feeding weights) with different food‐occurrence frequencies (15‐, 30‐ or 60‐s interfood intervals) in a within‐subjects design. Increases in food deprivation and food frequency generally led to increased licking, with greater differences due to food deprivation as interfood intervals became shorter. Distributions of licking were modestly shifted to later in the interfood interval as interfood intervals lengthened, a result that was most marked under 90% food deprivation, which also resulted in flatter distributions. It would therefore appear that food deprivation modulates the licking rate and the distribution of licking in different ways. Effects of food deprivation and food frequency are adequately explained by a theory of adjunctive behavior based on delayed food reinforcement, in contrast to alternative hypotheses.

Abstract The functional approach to comparative cognition research is exemplified by Shettleworth's (2010) book Cognition, Evolution, and Behavior . In this book, Shettleworth brings together the evolutionary perspective of behavioral ecology, the relative simplicity of behavior analysis, and the diverse research programs of cognitive psychology. This approach does not avoid the use of cognitive terminology but uses it to generate testable hypotheses that have the potential to provide evidence for or against the cognitive hypothesis. Unlike behavioral ecology and cognitive psychology, this approach postulates contingency learning as the default account of behavior but tests cognitive hypotheses against the default alternative. In this review, I present the results of three lines of research as examples of the kind of research that has been used to test cognitive hypotheses: functional equivalence, cognitive mapping, and rehearsal processes, all of which are covered by Shettleworth. In each case, I would argue that these experiments would not have been conducted had it not been for the hypothesis that a cognitive process might be involved. Whether or not evidence is found for the existence of a cognitive process, the results of such experiments are of interest for what they tell us about behavior as well as for their heuristic value.