The Conditioned Theory: The Placebo Effect On Animals

The idea behind the conditioned theory can be best explained by Pavlov’s classic experiment on dogs. Pavlov observed that a neutral stimulus, such as a bell, could evoke the same response as the natural stimulus (food). For both stimuli the response was the same: hunger and the desire to eat. This is an example of a conditioned response (Stewart-Williams et al., 2004). Conditioned responses are also present in the placebo effect. Non-active stimuli have shown to have a healing effect after consistent association with stimuli which were scientifically proven, as they become conditioned. (Voudouris et al., 1990)

There are several studies that support the conditioned theory. Voudouris has shown that the conditioned theory is overruling the

This means researchers make the assumption that the placebo effect on animals is similar as in humans. For example, two researchers Ader and Cohen injected a saccharine-flavored liquid with the immunosuppressant cyclophosphamide in rats (Ader & Cohen, 1982). After a couple of times matching these solutions, it became evident that the saccharine solution alone effected the immune

From a medical point of view, when someone takes a placebo pill he believes he will get better. This idea will alleviate worry and stress levels (Lundh,2000). Neurologically, this will release hormones such as endorphins and dopamine (Haour,2005), which will enhance the immune system and therefore help curing a disease (Lundh,2000). In addition to this, a possibility could be that the effect of expectation is caused by alterations in other cognitions. To illustrate, a placebo that suppresses pain can decrease depressing thoughts and therefore enhance other