International Journal of Comparative Psychology

A long-standing debate in olfactory perception is whether hedonic responses to odors are learned or innate. To test the hypothesis that olfactory hedonic responses are acquired through associative learning with emotion, two experiments were conducted that varied with regard to whether a novel (“target” odor) was pre-experimentally pleasant or unpleasant and the emotional association was positive or negative. Participants were randomly assigned to an Experimental Group (odor + emotional association) and various Control Groups. Evaluations of the target odor and several common odors that were not explicitly part of the association procedures (anchor odors) were made: prior to the manipulations, postmanipulation, 24 h after the manipulation, and 1 week from the start date. In both experiments, evaluation of the target odor by all participants was comparable at premanipulation and responses to the anchor odors were unaffected by time or experimental condition. However in each experiment, post-emotional manipulation ratings to the target odor were significantly altered in the Experimental Groups and showed that odor perception had changed in accord with the emotional valence of the associated experience. These findings support the hypothesis that olfactory hedonic responses are learned through emotional associations and raise new methodological and theoretical questions for future research.