By Angela M. Thomas & Madeleine G. Mason
Dr. Cynthia Fast is a powerful example of how behavior analysts can, as Skinner urged, “act to save the world” (1987). As a doctoral student at UCLA she conducted research on rodent cognition and associative learning in pigeons and hermit crabs using approaches based in learning theory.
Dr. Fast went on to a post-doc position at Rutgers University where her work focused on olfactory processing and neuroimaging. In 2016, her expertise in learning, olfaction, and animal behavior led her to relocate to Morogoro, Tanzania, to take on her current role as head of Training and Behavioral Research at the global non-profit organization APOPO (the Dutch acronym for Anti-Personnel Landmines Detection Product Development). The mission of APOPO is to train scent-detection animals to accomplish humanitarian goals such as safe elimination of unexploded landmines and efficient testing of sputum samples for tuberculosis (APOPO, 2022).
To accomplish these goals, Dr. Fast and the APOPO Team have successfully trained African giant pouched rats, which have an excellent sense of smell, to respond to scent stimuli. Through association of the sound of a clicker with a food reinforcer (bananas, avocados, and peanuts, for example) the rats are conditioned to discriminate between target and superfluous scents. Positive reinforcement is presented when they emit an indication response to the target scent and ignore other, non-target odors. One of the target scents is trinitrotoluene (TNT), which is present in explosive remnants of war (Poling et al., 2010). The rat is fitted with a harness that is tethered to a guideline, each end held by a handler, allowing the animal to ‘walk a grid’ between handlers. When the rat detects TNT, it scratches at the earth. The handlers then mark the location for further inspection by demining personnel. A HeroRAT team can inspect an area the size of a tennis court in less than an hour – a feat which might take up to four days to complete with a metal detector – because the rats aren’t slowed down by false-positives from scrap metal. Though they may weigh as much as five pounds when fully grown, they are too light to activate the pressure-sensitive trigger. Once declared safe, cleared areas can once again be used by local communities. Through partnership with APOPO the country of Mozambique was declared free of all known land mines in 2015 (Morley, 2015).
Using a similar training framework, HeroRATs are also being utilized as a second-line testing technology in the fight against pulmonary tuberculosis (TB) (Fiebig et al., 2020). With approximately 10 million new cases globally each year, TB is the second leading cause of death by infectious disease behind COVID-19 (Zenner, 2021). Like COVID, TB is spread through infectious aerosol droplets. Diagnosis of active pulmonary TB is made through a culture process which takes weeks. HeroRATs are trained to detect TB-positive sputum samples much more rapidly by scent alone. APOPO estimates that their partnership with clinics has raised TB detection rates by 40% (Mgode et al., 2018).
Dr. Fast’s team is also working to increase the efficiency of HeroRATs’ scent detection training by including multiple target odors simultaneously in discrimination training (Webb et al., 2020). This work has yielded promising results suggesting that pouched rats can acquire five odor discriminations concurrently in fewer training sessions than currently working HeroRATs required to master detection of a single odor. This research has the potential to reduce the time, money, and other resources needed to achieve APOPO’s stringent standards of mastery, thereby enabling HeroRATs to do more of their life-saving work.
Of course, the rats are only able to do their work thanks to skilled human trainers and handlers. Thus, Dr. Fast and her team have also taken up research on maximizing trainers’ fidelity using behavioral skills training (BST), an empirically supported training strategy consisting of instruction, modeling, rehearsal, and feedback (Lewon et al., 2019). BST is provided to ensure trainers implement reinforcement procedures and collect data as specified by the training protocol, which has resulted in more reliable data on rats’ performance. Dr. Fast and her team are also looking ahead to other humanitarian issues in which HeroRATs can contribute to low-cost solutions, including detection of illegally trafficked animals and wildlife products.
The work of APOPO is a real-world embodiment of how the principles of behavior analysis can be utilized to affect positive and far-reaching changes. Thank you, Dr. Fast, for your work developing and implementing these training techniques, and for being a such a wonderful exemplar in our field. We are excited to see the future you help shape.
APOPO. (2022). We save lives by training animals to rid the world of landmines and tuberculosis. APOPO. Retrieved March 30, 2022, from https://www.apopo.org/en
Fiebig, L., Beyene, N., Burny, R., Fast, C., Cox, C., & Mgode, G. (2020). From pests to tests: training rats to diagnose tuberculosis. European Respiratory Journal, 55(3), 1-5. doi:10.1183/13993003.02243-2019.
Lewon, M., Webb, E., Brotheridge, S., Cox, C., & Fast, C. (2019). Behavioral skills training in scent detection research: Interactions between trainer and animal behavior. Journal of Applied Behavior Analysis, 52(3), 682-700. doi:10.1002/jaba.566.
Mgode, G. F., Cox, C. L., Mwimanzi, S., & Mulder, C. (2018). Pediatric tuberculosis detection using trained African giant pouched rats. Pediatric Research, 84(1), 99-103. doi:10.1038/pr.2018.40
Morley, J. (2015). Mozambique declared free of landmines. Arms Control Today, 45(8), 5.
Poling, A., Weetjens, B. J., Cox, C., Beyene, N., Bach, H., & Sully, A. (2010). Teaching giant African pouched rats to find landmines: Operant conditioning with real consequences. Behavior Analysis in Practice, 3(2), 19-25. doi:10.1007/BF03391761
Skinner, B. F. (1987). Upon Further Reflection. Prentice Hall.
Webb, E., Saccardo, C. Poling, A., Cox, C., & Fast, C. (2020). Rapidly training African giant pouched rats (Cricetomys ansorgei) with multiple targets for scent detection. Behavioural Processes, 174, 104085. doi:10.1016/j.beproc.2020.104085.
Zenner, D. (2021). Time to regain lost ground: Tuberculosis in the COVID-19 era. Eurosurveillance, 26(24), 2100564. doi: 10.2807/1560-7917.ES.2021.26.24.2100564