Performance decline by search dogs in repetitive tasks, and mitigation strategies

Abstract

a b s t r a c tDifferences between training and working contexts have the potential to be a major cause of deficits in performance of searching animals. Detection responses of individuals trained with high rates of target stimulus presentation tend to extinguish when moved to a new context where their rate of target encountering is low. This problem is acute with some contraband and people detection dogs where the rate of target encountering in the work context is significantly lower than during training. While the rate of extinction can be mitigated by planting known targets in the working contexts, this is often logistically difficult, dangerous, or impractical; an alternative solution would therefore be beneficial. Here, we explore the novel approach of adding non-contraband target stimuli to the training set and then presenting these innocuous targets periodically in the work context, thereby avoiding the logistic difficulties attached to the use of real contraband targets. Our rationale is that the search persistence caused by the innocuous targets could generalise to the real targets, thus increasing resistance to extinction in the latter. The potential problem with this approach is that dogs may learn to focus on the innocuous targets in the work context to the detriment of the real targets. In our experiments, 21 dogs were trained with three contraband (explosive) and one innocuous (non-explosive) odours. When they were transferred to a "work" context, they were separated into three groups, as follows: Group "0T" (zero target) were not exposed to any targets in the work environment; Group 1T (one target) were exposed to and rewarded on one innocuous target in the work environment; and Group 3T (three target) were exposed to and rewarded on three contraband targets in the work location. These regimens continued for six weeks during which time all dogs received two refresher training days away from their work location, where they were rewarded on all four target odours. Following this work phase, search and detection performance was tested in the work location for all stimuli. In the work phase, search vigilance in the 0T group dropped considerably compared with the 1T and 3T groups. Critically, when dogs were reexposed to all four targets in the work location at the end of the work phase, detection rates were significantly reduced for the 0T group, but were maintained on all targets for the 1T Abbreviations: SDD, scent detecting dogs; NE, non-explosive; DR, detection rate. 113 and 3T group. Our results show that rewarding search persistence with innocuous stimuli is potentially a successful strategy to maintain detection-dog performance across a range of trained contraband odours.Crown

Increasing the persistence of a heterogeneous behavior chain: Studies of extinction in a rat model of search behavior of working dogs

“…The present results may be useful for developing training methods for search dogs that promote search vigilance and target detection accuracy under conditions in which reinforced target encounters occur infrequently (Gazit et al, 2005; Porritt et al, 2015). …”

“…Although our laboratory procedure does not model every aspect of searching in dogs, it is clear that search dogs engage in a chain of two or more behaviors (Porritt et al, 2015). Therefore, partial reinforcement and noncontingent reinforcers could influence persistence of the responses in the chain.…”

“…Fortunately perhaps, most working dogs will encounter prolonged periods in which searching does not result in discovery of the target odor. Therefore, a great deal of search behavior will never yield a reinforcer and responding could undergo extinction (Porritt et al, 2015). …”

A low-cost, portable optical explosive-vapour sensor

“…Common methods such as canines have stringent and limited working practice in the field, in addition to occasional unpredictability or fitness-to-work of the canines [1,2].…”

Preconcentration techniques for trace explosive sensing

“…While animals can be used for trace vapour mine detection, alternative techniques that are fast-responding and highly sensitive with low probability for false detections would be a significant addition to a demining toolkit. Current methods to detect explosives on minefields include sniffer dogs and Ion Mass Spectrometry (IMS), which have drawbacks primarily in terms of training, upkeep, cost and behaviour in the former (Porritt et al, 2015), or cost, lack of selectivity, and reportedly high level of false positives in the latter (Caygill et al, 2012;Giannoukos et al, 2016).…”