Evidence that phenomenal olfactory content exceeds what can later be accessed.

Visual experience contains more information than can later be recalled, and this study tested whether the same distinction exists for smell. In two experiments, participants rated odor features (e.g., how banana-like) both while smelling and after the odor was removed. On some trials the ratings matched; on others they differed. Each odor was presented twice: for half the odors both trials were identical, for the rest one trial differed. The after-smelling rating was always the same for each odor, allowing reliability to be measured. Incongruent profiles were least reliable. Attempting to access specific odor features after the odor is gone is harder if those features were not attended during smelling, suggesting more information is available during smelling than can be accessed afterward.

Study at a glance

Abstract

Visual experience is information rich, but only a small proportion is available for later access. We tested for this distinction in olfaction. In two experiments (E1&2), participants undertook trials rating an odor's features (e.g., how banana-like?), the during-smelling-profile, followed by an after-smelling-profile, upon the odor's removal. On some trials during and after-smelling-profiles were identical and on others they were different. Each trial with a particular odor was repeated. For half the odors both trials were identical (congruent) and for the remainder, one was different and the other identical (incongruent). Crucially, the after-smelling-profile was always the same for each odor, allowing reliability to be measured. E1&2 revealed that incongruent profiles were the least reliable. Attempting to access particular odor features in an odor's absence is harder if those features were not attended during smelling. This suggests more information is available during smelling, than can be accessed after the odors removal.