Sequential Effects in Odor Perception

Introduction
Our visual, auditory, and tactile perception is not solely determined by what we process at a given moment in time, but also determined by what we perceived recently. These sequential effects can either be negative (repulsive) or positive (assimilative). Here, we investigated whether such sequential effects also occur in odor perception.

Method
Participants rated a sequence of 40 different odors (varying widely in hedonic valence) on four different characteristics (intensity, familiarity, valence, and arousal). For each of these characteristics, we conducted an inter-trial analysis, based on whether the rating on the preceding trial was low or high.

Results
We found a positive serial dependence for both odor intensity and familiarity ratings. That is, the rating on the current trial was higher when the rating on the previous trial was high than when the rating on the previous trial was low. We observed no sequential effects for odor valence and arousal ratings.

Conclusion
The olfactory system integrates previous stimuli into the current perception of intensity and familiarity.

Implications
The current findings may be relevant for marketing applications and may guide the design and use of olfactory-enhanced virtual and augmented reality systems.