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How Psychologically Conditioned Rats Are Defusing Landmines

Ratting out the reprehensible.

Key points

  • African giant pouched rats can be trained to sniff out landmines.
  • Classical conditioning combined with operant conditioning is effective in training "HeroRats."
  • Trained rats have cleared land mines in countries ranging from Cambodia to Zimbabwe.

The African giant pouched rat (also known as the Gambian pouched rat) is a docile, intelligent rodent that weighs about nine pounds when fully grown. A non-profit organization in Belgium trains them to sniff out landmines. They can also be trained to detect blood samples that are positive for tuberculosis.

APOPO, which in Dutch is the acronym for “Anti-Persoonsmijnen Ontmijnende Product Ontwikkeling” (in English: Anti-Personnel Landmines Detection Product Development) has deployed its “HeroRats” from Asia to Africa. Even at nine pounds, the rodents are too small to trigger landmines, so their size, gentle nature, keen sense of smell, and trainability make them ideal landmine detection specialists.

Classical Versus Operant Conditioning

You probably know that Ivan Pavlov trained his dogs to salivate at the sound of a bell by ringing it at feeding time. Normally, the dogs salivated involuntarily at the sight and smell of food. Soon, however, the ringing bell caused automatic salivation, even without food. This is classical conditioning—an unrelated stimulus at or near the time of a reward or punishment becomes mentally associated as the cause of, or precursor to, the reward or punishment.

Here’s an example of a classical conditioned response in anticipation of a punishment. Suppose children can hear the sound of their father’s car when he arrives home from work. This particular father usually begins drinking as soon as he’s in the house and continues until he becomes drunk and abusive. The children live in fear of his unpredictable violence. Eventually, the mere sound of his car may be enough to elicit strong feelings of fear and dread.

In classical conditioning, the unrelated stimulus—a ringing bell or the sound of a car—comes before the reward or punishment. Operant conditioning withholds the stimulus until after the desired behavior occurs. For example, a child might get a cookie every time he or she remembers to put away toys after playing. If the toys are left out, the reward is withheld.

How APOPO Trains HeroRats

To train their HeroRats, APOPO uses both methods. Landmine detection training begins with rat pups being handled and socialized with humans. At about ten weeks of age, Pavlovian (classical) training begins. A handler offers the rats food and simultaneously activates a clicker. The rats learn to associate clicking with food.

In the next phase of training, the rats are exposed to tea infusers containing a sample of TNT. When a rat touches one of the infusers, the trainer clicks and gives the rat food. The method has now transitioned to operant conditioning. The rats learn that touching the metal object results in a reward.

At the advanced level, rats are exposed to several tea infusers, some containing TNT and some not. The rats receive no reward for touching an empty tea infuser, but are always rewarded when they touch TNT-positive infusers. Now the rats have learned that all metal objects are not equal. Only those with the TNT smell provide a food reward.

Having progressed from classical through operant conditioning, the rats then practice their new skills outside. Trainers bury TNT-positive tea infusers, which prompts the rats to dig them up. This scratching at the ground will become the rats’ means of alerting their handlers to the presence of landmines.

Protecting Humans and Animals Alike

Abandoned landmines pose threats to both humans and wildlife. In Africa, mines have killed and maimed elephants and other indigenous species. When the HeroRats have cleared an area of land, it can be returned to the community for cultivation or set aside as wildlife habitat. APOPO and their cat-sized African rats fall somewhere in a twilight zone between the improbable and the remarkable.

A tip of the hat to Jacqueline Hartley, who brought the HeroRats to my attention.

© Dale Hartley. Connect with me on social media.

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