Patients' pretreatment expectations of chemotherapy-related nausea are an independent predictor of anticipatory nausea.

Based on extensive research with animals, classical conditioning theorists have come to regard contingency as the primary factor in the development of conditioned responses. However, recent experimental work with humans has suggested the possibility that participant expectations may also directly contribute to the development of conditioned responses. To date, this phenomenon has not been investigated in clinical settings. Anticipatory nausea (AN) in chemotherapy patients, widely viewed as the best established example of classical conditioning in clinical medicine, provides an opportunity to examine the contributions of patient expectations to the development of a conditioned response outside the laboratory. The present study of 59 breast cancer patients supported the hypothesis that pretreatment patient expectations make a significant (p < .03) contribution to the development of AN after statistically controlling for the strongest conditioning predictor, contingency. These data imply that patient expectations should be considered when evaluating conditioned responses to aversive medical treatments.