The information that we are aware of may differ markedly from what was originally received in our brain. The brain completes the information received, filling in gaps and eliminating uncertainty. This happens both with visual images, and with the read text, and with the speech perceived by ear, and with the feeling of the position of the body in space. Due to this, the processing is faster and usually gives a more accurate result. To complete the information, we use any available hints and keys. And this process is the more intense, the more uncertain the information received, that is, the more different ways to interpret it.
One of the most obvious and studied examples is the processing of information about the taste of food and drinks. It is known that the taste is influenced by the brand, packaging and information placed on it about the composition of food. This is why professional wine tastings are conducted blindly: this helps to eliminate the influence of expectations caused by the brand, grape variety and year of harvest indicated on the label. Try experimenting with one of your friends who consider themselves wine experts. You will see that when testing blindly, not every wine connoisseur can tell the difference between a 1961 Château Pétrus and an inexpensive Italian from a nearby Department store. The effect will be even brighter if you secretly pour inexpensive wine into a bottle from an expensive and well-known brand.
Pain is even more affected than other sensations. This was especially evident in a curious experiment in which participants were trained to a certain relationship between the force of pain and a neutral signal. The volunteers received a pain-inducing heat stimulus, which was weak if the green light came on before it, and strong if it was red. In the next stage, they were unknowingly exposed to medium-intensity pain, regardless of which light bulb, green or red, lit up before that. The subjects still described the pain after the green light as mild, and after the red light as severe. In terms of pain unknown signal intensity of the brain used for forming the feelings are the clues that were in his possession.
It can be assumed that at the second stage only the responses to the experimenter varied, and the sensations of the subjects corresponded to the intensity of the pain stimulus, that is, they were the same. But functional tomography showed more pronounced activation of pain-related areas of the brain in cases where the red light was on. This suggests that the difference in responses reflected the difference in feelings. It is interesting that the tips received from other people affected no less than their own experience. In one version of the experiment, the subjects observed at the first stage of decoy ducks, which portrayed a strong pain after the red light and weak – after the green. The interpretation of the pain of unfamiliar intensity at the next stage also depended on the color of the light bulb.
Given the way the brain processes incoming information, the placebo effect is no longer surprising. The brain supplements the signals received from the body, depending on the expectations dictated by the ideas about the effectiveness of a particular treatment. If we expect relief from the drug, we may feel the unpleasant sensations or unwanted emotions recede.
During the clinical experiment, the participants were divided into two groups: one was treated with acupuncture, and the other – with a placebo simulation, creating only the illusion of piercing the skin with a needle. Before the experiment, participants were warned that they could get both real acupuncture and fake, but would not know which group they would end up in. At the end of the procedure, they were asked if they thought it was real acupuncture or fake, and then asked to evaluate the analgesic effect. The pain reduction in both groups was the same. But in both cases, those who believed they had undergone actual acupuncture reported greater improvement than those who thought they were in the placebo group.
Thus, the only condition for the occurrence of the placebo effect is our positive expectations. They may rely on experience, doctor’s promises, or information received from other people. Interestingly, the analgesic effect of a placebo is enhanced if the patient has been given a real analgesic several times before. This phenomenon can be explained both by the fact that the experience of successful analgesia increases the expectations of the next drug intake, and by the fact that the body in a sense learns to anesthetize.
In this case, the placebo effect can be discussed in terms of the emergence of a conditioned reflex. A conditioned reflex is the formation of a response to a stimulus that was initially neutral, but ceased to be so because the brain associated it with an innate unconditioned reflex. For example, saliva from the smell and type of food is an unconditional reflex. If, as in the famous Pavlov experiment, you repeatedly accompany a meal with a call, there will be a conditioned reflex-saliva will be released at the sounds of the call, initially a neutral stimulus.
When it comes to people, this process is often called associative learning, emphasizing that, unlike animals, we do not have unconscious automatism. However, contrary to what we were taught in school, and in animals, conditioned reflexes also occur with the participation of higher parts of the brain associated with cognitive processes. They can be seen as a change in the meaning of a previously neutral stimulus.
☛ One of the common arguments against the psychological nature of the placebo effect is that it is observed even in animals and infants. The logic here is that animals and small children are not intelligent, can not understand that they are being treated, and therefore can not expect to improve. From this it is concluded that the placebo effect works in some other, magical way.
In fact, these observations do not contradict the modern understanding of the mechanisms of the placebo effect. Pavlov also described how, after several injections of morphine, dogs developed morphine-like reactions when they were put back in the same environment. And if we are more comfortable with the idea that animals and young children are not able to consciously wait for improvement, the placebo effect in their case can be fully described in terms of conditioned reflex formation.
However, the first thing to remember is that the placebo effect in young children and animals is a change in subjective symptoms in those we can’t even talk to. And all reports about it are caused solely by the way observers (parents, the owner of the animal) interpreted the change in the behavior of the patient. This interpretation may be deeply flawed. First, it may be affected by the fact that the observer always knows that the patient has received a placebo, and is waiting for signs of improvement. Second, without controlled experiments, we can’t be sure that we didn’t take natural recovery as a placebo effect.