What are placebo effects?
Some people think that "placebo effect" is the label given to cases of people believing they've recovered or perceiving their symptoms to have decreased or gone, when those people have received no medically active intervention: so, they've received a sugar pill perhaps, or a sham surgical intervention of some kind and in response perceive their symptoms to have improved or believe themselves to have recovered. However, this is not what we mean by "placebo effect", it's actually far more mind-blowing than that!
It is not simply that people believe or perceive themselves to have recovered or believe that the condition has gone into remission, it is that they HAVE, as a matter of clinically verifiable fact, recovered as if having received a pharmaceutically active or surgical intervention. Daniel E. Moerman’s book Meaning, Medicine and the "Placebo Effect" is replete with examples, as are many other papers and books on placebos. This much about placebos is uncontroversial, even though it is, as noted above, pretty mind-blowing.
To expect something one has to represent, in the form of a belief, the putative state of affairs one is expecting and the problem is that in many documented cases of placebo responses there is simply no evidence that those responding to the sham treatment have such a belief (unlike in the coffee example). However, and this is the more telling point, there are many cases of placebo responses where those responding to sham treatments in placebo-type ways do not have the epistemic resources, or even access to them, such that they might form the required belief. So, it is not merely that there are cases of "placebo responses" where those who respond do not appear to have the beliefs that would be required in order to form the expectation, it is that they don't have access to the data that would be required to serve as the 'building blocks' for such an expectation.
So, what of expectation now? If, as the response-expectancy crowd want to do, we hold on to expectancy as an explanation for "placebo responses", then we need to provide warrant for our having extended the grammar of “to expect”, such that in this use it is not internally related to, it does not invoke, a propositionally structured belief, a representation of a state of affairs. This, in turn entails having access to the epistemic resources, which, recall, we have seen are simply unavailable in many cases of placebo responses.
We can put the argument of the last paragraph less abstractly: if you want to stick with expectancy, you owe us an explanation as to how someone can expect something while not being in a position to know what it is they are expecting, i.e. how can one expect something without being able to specify or represent the something they are expecting?
Alternatively, we can leave the grammar of 'to expect' as it is, stop trying to square this particular circle, and instead drop the overly restrictive reliance on response-expectancy as a global explanation for "placebo responses". Then, instead, we might talk more broadly about meaning responses (as Dan Moerman does), and set about, via ethnographic investigations of people responding in medically significant ways to pharmaceutically and surgically inert interventions, gaining better understanding of medically significant meaning responses.
Here we are talking about the world having meaning in a way that does not demand that we first have the resources to form beliefs about (possible) states of affairs in the world, for we don't need to expect something to cure us for us to be cured when we have received a sham treatment. Rather, we move beyond such a representationalist picture of cognition, to more enactive or even ethnomethodologically-informed accounts.