Odors: implicit memory and performance effects.

In order to assess the influence of odors on human performance and implicit memory for odors, 108 subjects completed a variety of tests in weakly scented (jasmine, lavender or odorless) rooms without having been made aware of the odor. After a 30 min interval the subjects were shown slides of different surroundings, including the room they had been in, and were requested to rate how well a set of 12 odors, including a blank, would fit to these surroundings. Half of these contexts contained visual cues related to two of the presented odors (leather and coffee). After the rating of fit the subjects had to rate the odors for pleasantness, were asked to identify the odors with their correct names and to tell where and when they had last smelled these odors. One subject remembered smelling the odor (jasmine) in the room and was discarded from the analysis of the results for the rating of fit. None of the others reported recollection of the experimental odors. The results showed that in general jasmine had a negative and lavender a positive effect on test performance. If an odor-related visual cue was present in the context, the related odor was always rated highest in fit to that context. Furthermore, the subjects working in rooms with an odor subsequently assigned this odor to the visual context of that room to a significantly higher degree than subjects working in rooms with different odors. Since none of the subjects reported that they had smelled the odor in the rooms where performance testing took place, it was concluded that the memory for these odors was implicit. Further analysis showed that such memory was only found in subjects who were unable to supply the right name for the odor. The possible consequences of this latter finding for understanding the relationship between sensory (episodic) and semantic odor memory are discussed.