Patients' expectancies and improvement in treatment: the shape of the link

It has been hypothesized (a) that patients' expectancies for therapeutic gain are linked to the clinical improvement that the patients realize in treatment; and (b) that patients' expectancies may play a causative role in such improvement. The first hypothesis has received empirical support, but the second has not. This study tested the causativeinterpretation of patients' expectancies and a second interpretation, which states that patients' expectancies predict, but do not cause clinical improvement. The shape of thelink between expectancy and improvement for hospitalized schizophrenics was explored. Based on motivation research it was reasoned that a curvilinear relationship between expectancy and improvement would support a causative interpretation and that a linear relationship would support a predictive interpretation of the nature of expectancy. Multiple regression analyses found a linear relationship between expectancies and objective measures of improvement for the patients, but no evidence of a curvilinear relationship between these measures. The results were interpreted as supporting a predictive interpretation of the expectancies of hospitalized schizophrenic patients.