Sentence:  It is clear that we cannot distinguish the sane from the insane in psychiatric hospitals. ... I and the other <WSD>pseudopatients</WSD> in the psychiatric setting had distinctly negative reactions. We do not pretend to describe the subjective experiences of true patients. Theirs may be different from ours, particularly with the passage of time and the necessary process of adaptation to one's environment. But we can and do speak to the relatively more objective indices of treatment within the hospital. 
Meaning of the word marked with <WSD> tags:  A person who poses as a patient so that  research may be conducted or staff trained.