Automated Canine Scent-Detection Apparatus: Technical Description and Training Outcomes.

To date, laboratory scent-detection work with dogs has been a manual process whereby some or all aspects of the procedures are mediated by researchers. Automation of this process would eliminate issues associated with cuing, subjectivity in data collection, and reinforcement delivery. Herein, I describe an automated apparatus that can accommodate almost any type of sample that can be brought into the laboratory. The apparatus consists of a 17-segment carousel that rotates behind a panel. Dogs can access a single sample at a time through a port in the panel. Infrared beams are used to detect sample observations and indications, and a dog-activated switch is used to advance the carousel to the next sample. Correct indications are reinforced with an automated feeder. After screening 12 dogs, 5 dogs were selected and trained to use the apparatus to classify samples containing amyl acetate. All dogs achieved hit rates and correct rejection rates at or near 100% in fewer than 25 half-days of training (mean: 19.6, range: 12-24). These data suggest that the apparatus can be used to obtain accurate sample classification without excessive training requirements. Future improvements to the apparatus and training protocols may reduce the training requirements further.

Experimental analysis of canine behavior and cognition: Introduction to the special issue.

Over the last 3 decades, the use and popularity of canid models for basic and applied behavioral research has grown dramatically, and for good reasons. Dogs are uniquely among the human world, living and working in our homes and places of employment while an even greater population lives on the outskirts of human life, scavenging and navigating the city life. This provides a rich continuum of environmental contexts for the canine experience, leading to some unique and even human-like behaviors in animals. The articles in this special issue provide additional insight into factors that influence canine welfare, methods for evaluating dogs' preferences and the reinforcing effectiveness of stimuli, trick learning and retention, concept learning, and scent detection performance under sparse reinforcement conditions. Here we provide an overview of these articles and their contribution to our understanding of canine behavior.

Extracting spatial information from temporal odor patterns: insights from insects.

Extracting spatial information from temporal stimulus patterns is essential for sensory perception (e.g. visual motion direction detection or concurrent sound segregation), but this process remains understudied in olfaction. Animals rely on olfaction to locate resources and dangers. In open environments, where odors are dispersed by turbulent wind, detection of wind direction seems crucial for odor source localization. However, recent studies showed that insects can extract spatial information from the odor stimulus itself, independently from sensing wind direction. This remarkable ability is achieved by detecting the fine-scale temporal pattern of odor encounters, which contains information about the location and size of an odor source, and the distance between different odor sources.

Reexamining nodality in equivalence classes.

Equivalence classes are defined according to the substitutability, or functional similarity, of the stimuli within a stimulus class. Several studies have demonstrated that the degree of functional similarity between stimuli in a class is dependent, in part, upon the number of nodes (intervening stimuli) between the stimuli. Higher nodal number is related to lower functional similarity. This effect is referred to as "nodality." There are three key factors that have not been simultaneously controlled for in the relevant studies: priming effects, reinforcement during training, and multiple stimulus functions of stimuli (sample, comparison, or both). In the present experiment, controlling for these factors, two 6-member, 4-node equivalence classes were established, and a within-class preference assessment was used to evaluate nodality. Of 12 participants, five achieved criterion accuracy (90%) during testing. These participants demonstrated nodality, showing preference for stimuli that were nodally proximal to a sample in the preference test. When distal comparisons were chosen, participants took longer, on average, to make the selection compared to selections of proximal stimuli. These findings are consistent with earlier studies demonstrating nodality, which suggests that nodality is a robust phenomenon and not an artifact of the factors that were controlled for in the present study.

Response-strengthening effects of same- and different-context DRA training: The effects of two disruptors.

Differential reinforcement of alternative behavior (DRA) involves placing problem behavior under extinction and simultaneously reinforcing a desirable behavior. Recent research revealed that, as predicted by Behavioral Momentum Theory, DRA may also increase the persistence of the problem behavior. This research has also shown that a different approach to DRA, in which an alternative behavior is trained in a separate context from the target behavior, produces less persistence than the standard procedure. The research on this phenomenon, so far, assessed persistence using extinction as the disruptor. DRA, however, is often implemented under conditions in which extinction of the problem behavior is not feasible. This study evaluated persistence of problem behavior following same- and separate- context DRA training using an alternative disruptor, an additional source of reinforcement. Following a successful reproduction of a previous study of extinction as a disruptor but with domestic hens, this study produced similar findings using an additional source of reinforcement as the disruptor. These findings add to the evidence that alternative DRA arrangements may avoid the response-strengthening effects found with traditional DRA procedures. The findings also demonstrate that disruptors other than extinction can be used to investigate response persistence following DRA and other procedures.

Resurgence increases with repetition.

Resurgence refers to a behavioral process in which a recent response is extinguished (or reinforcement conditions worsen) and a previously extinguished response recurs. In previous research, resurgence has been reliably produced when the resurgence procedure is repeated. Changes in the degree of increase of the resurging response across iterations of the procedure have been inconsistent, however, with some studies showing increases and some showing no changes or decreases in resurgence magnitude. The present study examined the nature of resurgence across repeated iterations of the conventional resurgence procedure by exposing four pigeons to the resurgence procedure six times in succession. In the first condition of the resurgence procedure, pecks on one key (e.g., the left) were reinforced under a variable-interval (VI) 30-s schedule. In the second condition pecks on that key were extinguished, and pecks on another key (e.g., the right) were reinforced under the same schedule. In the final condition there were no programmed consequences for either response. Resurgence was observed in 21 of 24 opportunities (87.5%). Iteration-over-iteration increases in resurgence were observed in 15 of 20 opportunities (75.0%), and this increase was found to be statistically significant. These findings demonstrate that, under certain conditions, resurgence generally increases in magnitude with repeated exposure to the procedures that generate it.

Influences of breath sample re-use on the accuracy of lung cancer detection dogs.

Evaluations of dogs as lung cancer detectors using breath samples have produced a variety of results, some quite promising. Breath samples are typically collected onto a substrate and stored in a sealed container when not in use, but volatile compounds dissipate when the substrate is exposed during training and evaluation sessions. Collection of appropriate samples for training and testing dogs requires significant resources and strict control of recruitment and sample collection processes. Therefore, some researchers re-use samples while training dogs. No systematic evaluation of the effect of sample re-use on dogs' training performance has been conducted, so the influence of this potentially important training factor is not known. We trained seven dogs to indicate the presence of lung cancer positive breath samples using an automated apparatus. The samples were stored at -60 °C or -80 °C. Samples from 460 individuals who were classified as positive or negative for lung cancer were used for training samples. Individual samples were presented to dogs up to four times over a period of 2 years. As sample re-use increased, sensitivity declined (-6.65,p= < .001, 95% CI [-10.56, -2.76]), specificity increased (2.87,p= .036, 95% CI [.19, 5.55]), and the dogs' bias shifted in the direction of a negative indication bias (-.094,p= < .001, 95% CI [-.149, -.39]). However, there were no significant changes in the measure associated with the detectability of the target (-0.30,p= .285, 95% CI [-.087, .26]). All observed changes in performance across sample re-use were small. Therefore, these findings suggest that sample re-use may be appropriate for training, but additional research is required to determine which factors underly changes in performance as breath samples are re-used.

What Can We Learn by Treating Perspective Taking as Problem Solving?

Perspective taking has been studied extensively using a wide variety of experimental tasks. The theoretical constructs that are used to develop these tasks and interpret the results obtained from them, most notably theory of mind (ToM), have conceptual shortcomings from a behavior-analytic perspective. The behavioral approach to conceptualizing and studying this class of behavior is parsimonious and pragmatic, but the body of relevant research is currently small. The prominent relational frame theory (RFT) approach to derived perspective taking asserts that "deictic framing" is a core component of this class of behavior, but this proposal also appears to be conceptually problematic. We suggest that in many cases perspective taking is problem solving; when successful, both classes of behavior involve the emission of context-appropriate precurrent behavior that facilitates the appropriate response (i.e., the "solution"). Conceptualizing perspective taking in this way appears to have many advantages, which we explore herein.

A procedural analogue of prey detection and applied signal detection.

Researchers have employed a variety of laboratory analogues of cryptic prey detection and applied signal detection to study factors influencing learning and performance in these ethological and applied scenarios. However, these procedural analogues do not appear to map closely onto their "real-world" counterparts, particularly with respect to the role of the "yes" (i.e., "attack") response and the payoff for this response (or its absence) on signal-present and signal-absent trials. Using domestic hens, we developed a procedural analogue in which a "yes" response requires some time to emit; such responses were reinforced only in the presence of a signal. In Experiment 1, we evaluated the influence of the "yes" response requirement by manipulating the number of responses required to qualify as a "yes" response. As the "yes" response requirement was increased, bias toward responding "no" increased, revealing that this is a critical factor controlling accuracy in this procedure. In Experiment 2, we evaluated the influence of signal probability and reinforcement rate on signal detection accuracy and found that neither of these factors significantly influenced accuracy or bias. These findings suggest that this procedural analogue may represent a valuable alternative for studying behaviour in relevant signal detection scenarios.

Motivating Operations and Negative Reinforcement.

The motivating operations concept has improved the precision of our approach to analyzing behavior; it serves as a framework for classifying events that alter the reinforcing and punishing effectiveness of other events. Nevertheless, some aspects of the concept are seriously flawed, thereby limiting its utility. We contend in this article that the emphasis it places on the onset of some stimuli (putative motivating operations) making their offset a reinforcer in the absence of a learning history (i.e., in the case of unconditioned motivating operations), or because of such a history (i.e., in the case of reflexive conditioned motivating operations), is of no value in predicting or controlling behavior. It is unfortunate that this pseudo-analysis has been widely accepted, which has drawn attention away from actual motivating operations that are relevant to negative reinforcement, and led to conceptually flawed explanations of challenging human behaviors that are escape-maintained. When used appropriately, the motivating operations concept can help to clarify the conditions under which a stimulus change (in particular, stimulus termination) will function as a negative reinforcer. From both a theoretical and a practical perspective, rethinking the application of the motivating operations concept to negative reinforcement is advantageous. Herein, we explore the implications of doing so with the aim of encouraging relevant research and improving the practice of applied behavior analysis.

Motivating Operations and Discriminative Stimuli: Distinguishable but Interactive Variables.

The motivating operations concept has been of considerable interest and practical value to behavior analysts, including practitioners. Nonetheless, the concept has generated substantial controversy and has significant limitations. To address some of these limitations, we suggest that it would be wise to redefine motivating operations, to deemphasize the importance that has historically been placed on subtypes of conditioned motivating operations, to emphasize how motivating operations and discriminative stimuli interact, and to further examine the kinds of environmental changes that alter the reinforcing value of particular kinds of stimuli. These suggestions are detailed elsewhere and summarized in this article.

Motivating operations and stimulus control.

The motivating operations concept has generated substantial conceptual analysis and research interest. Following an analysis of how motivating operations affect behavior, one which emphasizes the interactive role of motivating operations and discriminative stimuli, we propose: a) redefining motivating operations as operations that modulate the reinforcing or punishing effectiveness of particular kinds of events and the control of behavior by discriminative stimuli historically relevant to those events, b) dropping the distinction between behavior-altering and function-altering effects of motivating operations, and c) reducing or eliminating emphasis on conditioned motivating operations. This reconceptualization of the motivating operations concept is intended to increase its value in predicting and gainfully changing behavior.

Tuberculosis detection by pouched rats: Opportunities for reinforcement under low-prevalence conditions.

Giant African pouched rats (Cricetomys ansorgei) have been employed successfully in two operational tuberculosis-detection projects in which they sniff sputum samples from symptomatic individuals who have visited tuberculosis clinics. The prevalence of pulmonary tuberculosis in this population is high, approximately 20% in the regions where the rats have been used. If the rats are to be used to screen individuals from lower-prevalence populations, their performance under such conditions must first be evaluated. In this study, the prevalence of tuberculosis-positive samples presented to eight pouched rats was reduced to approximately 5%, and the percentage of known-positive samples included as opportunities for reinforcement was varied in sequence from 10 to 8, 6, 4, 2, 4, and 2. Liquid food reinforcers were delivered for identification responses to known-positive samples and at no other time. The rats' accuracy was clinically and statistically significantly lower at 2% than at the other values. These results indicate that the rats can perform well in low-prevalence scenarios but, if they are used under the conditions of the present study, at least 4% of the samples presented to them must be opportunities for reinforcement.

Active tuberculosis detection by pouched rats in 2014: More than 2,000 new patients found in two countries.

Tuberculosis (TB) is a major problem in poor countries because sensitive diagnostic tools are unavailable. In 2014, our pouched rats evaluated sputum from 21,600 Tanzanians and 9,048 Mozambicans whose sputum had previously been evaluated by microscopy, the standard diagnostic for TB. Evaluation by the rats revealed 1,412 new patients with active TB in Tanzania and 645 new patients in Mozambique, increases of 39% and 53%, respectively, when compared to detections by microscopy alone. These results provide further support for the applied use of scent-detecting rats.

Effects of schedules of reinforcement on pouched rats' performance in urban search-and-rescue training.

Standard operating procedures have been developed to train Cricetomys to locate humans in collapsed structures and return to the release point on command. The present study demonstrated that the schedule of reinforcement for target location influences the rats' performance. Rats required more time to locate targets when no reinforcement was arranged for target location but less time to return to the release point. These findings suggest that training conditions should be based on the priority assigned to target location and return in an operational scenario.

Giant African pouched rats (Cricetomys gambianus) that work on tilled soil accurately detect land mines.

Pouched rats were employed as mine-detection animals in a quality-control application where they searched for mines in areas previously processed by a mechanical tiller. The rats located 58 mines and fragments in this 28,050-m(2) area with a false indication rate of 0.4 responses per 100 m(2) . Humans with metal detectors found no mines that were not located by the rats. These findings indicate that pouched rats can accurately detect land mines in disturbed soil and suggest that they can play multiple roles in humanitarian demining.

Training pouched rats to find people.

Giant African pouched rats equipped with video cameras may be a tenable option for locating living humans trapped under debris from collapsed structures. In the present study, 5 pouched rats were trained to contact human targets in a simulated collapsed building and to return to the release point after hearing a signal to do so. During test sessions, each rat located human targets more often than it located similar-sized inanimate targets on which it had not previously been trained and spent more time within 1 m of the human target than within 1 m of the other targets. Overall, the rats found humans, plastic bags containing clothes, and plastic bags without clothes on 83%, 37%, and 11% of trials, respectively. These findings suggest that using pouched rats to search for survivors in collapsed structures merits further attention.

Evaluation of Giant African Pouched Rats for Detection of Pulmonary Tuberculosis in Patients from a High-Endemic Setting.

BACKGROUND: This study established evidence about the diagnostic performance of trained giant African pouched rats for detecting Mycobacterium tuberculosis in sputum of well-characterised patients with presumptive tuberculosis (TB) in a high-burden setting. METHODS: The TB detection rats were evaluated using sputum samples of patients with presumptive TB enrolled in two prospective cohort studies in Bagamoyo, Tanzania. The patients were characterised by sputum smear microscopy and culture, including subsequent antigen or molecular confirmation of Mycobacterium tuberculosis, and by clinical data at enrolment and for at least 5-months of follow-up to determine the reference standard. Seven trained giant African pouched rats were used for the detection of TB in the sputum samples after shipment to the APOPO project in Morogoro, Tanzania. RESULTS: Of 469 eligible patients, 109 (23.2%) were culture-positive for Mycobacterium tuberculosis and 128 (27.3%) were non-TB controls with sustained recovery after 5 months without anti-TB treatment. The HIV prevalence was 46%. The area under the receiver operating characteristic curve of the seven rats for the detection of culture-positive pulmonary tuberculosis was 0.72 (95% CI 0.66-0.78). An optimal threshold could be defined at ≥ 2 indications by rats in either sample with a corresponding sensitivity of 56.9% (95% CI 47.0-66.3), specificity of 80.5% (95% CI 72.5-86.9), positive and negative predictive value of 71.3% (95% CI 60.6-80.5) and 68.7% (95% CI 60.6-76.0), and an accuracy for TB diagnosis of 69.6%. The diagnostic performance was negatively influenced by low burden of bacilli, and independent of the HIV status. CONCLUSION: Giant African pouched rats have potential for detection of tuberculosis in sputum samples. However, the diagnostic performance characteristics of TB detection rats do not currently meet the requirements for high-priority, rapid sputum-based TB diagnostics as defined by the World Health Organization.