A recent study in the journal Animal Cognition involving drug and explosive detection dogs has been widely reported in the online media (e.g. Medical News Daily, Sacramento Today, etc). The study, conducted at the University of California at Davis, was cleverly designed to explore the unconscious influence of detection dog handlers on their canine partners. It provides an excellent example of how greatly the beliefs and expectations of humans can unintentionally affect the behavior of dogs, even when both the human and the dog are highly trained professionals. The study is interesting in its own right, but it is also relevant to veterinary medical research since the problem of the unintended effects of human beliefs and expectations creates significant challenges for assessing the efficacy of veterinary medical therapies.
In this study, 18 detection teams were tested in each of 4 different rooms, none of which contained any explosives or drugs as a target. Therefore, any positive alert response from the dogs was an incorrect (or false positive) response. Handlers were told that a red piece of paper would be present in some rooms and would indicate the location of a substance the dog should detect. In reality, this piece of paper was a decoy intended only to create and expectation in the mind of the handlers that their dogs should exhibit a positive response. The 4 rooms contained the following:
1. No target, no paper decoy for the handler, no scent decoy for the dog
2. No target, a paper decoy for the handler, no scent decoy for the dog
3. No target, no paper decoy for the handler, a scent decoy for the dog (sausages and tennis balls)
4. No target, a paper decoy for the handler at the same location as a scent decoy for the dog (sausages and tennis balls)
Each of the teams was tested in each room, and there were a total of 225 incorrect responses (in which the dog sat/lay down and/or vocalized as it had been trained to do to indicate it had detected a target substance). There were false responses in all rooms, but interestingly there were more mistakes in the rooms with only a paper decoy for the handler than in those with a scent decoy for the dog. This would seem to suggest that the unconscious behavioral cues given by the handler affected the dogs’ performance even more than the presence of food or toys!
It is easy to see the implications of this finding for veterinary medicine. Many of the symptoms we look at in evaluating the effect of treating a patient, and many of the variables we measure in research studies of medical treatments, rely on owners or veterinarians observing the behavior of our animal patients. Most attempts to assess pain, itching, activity level, nausea, appetite, behavior and many other key indicators of health are ultimately dependant on subjective interpretation by owners and veterinarians.
We already know that our own expectations and biases can influence what we see and how we interpret it. That is, after all, the major basis for the placebo effect, and why it disappears when we don’t know if the patient is getting a real treatment or a placebo.
But what this study suggests is that the patients’ behavior is likely also affected by our expectations and biases. This is yet another element to the placebo-by-proxy effect, in which ineffective therapies are believed to be working because of non-specific treatment effects (aka placebo) on the owners or the doctors evaluating the treated patients. One of the best examples of this is the use of glucosamine for arthritis in pets, which the balance of the evidence pretty clearly shows doesn’t work but which many veterinarians and owners cling to tenaciously as a useful therapy regardless.
A study like this one shows quite clearly how our expectations and beliefs strongly effect the behavior of our dogs. And this was a study of experienced professional handlers who undoubtedly had been trained in how to avoid misleading their canine partners. Those of us without such training or unaware of the risks of such unconscious influences are likely at even greater risk for unintentionally changing our pets’ behavior in ways that conform to our beliefs. Could our dogs play more, scratch less, eat better, seem happier, or otherwise appear to benefit from treatments we give them partly because we want them to and we expect they will? This study suggests the answer is “Yes!” and reinforces the importance of properly controlled research in evaluating medical therapies.