The idea that olfaction and emotion are closely linked has long been a pervasive belief in people’s minds. But how much of this belief is fact, and how much just folk wisdom? Apart from the popular view, psychological research has shown that odours car influence mood, evoke powerful experiences of pleasure or displeasure and produce sensations of arousal or relaxation. Moreover, odours seem to be a very powerful cue in bringing emotional experiences from memory back to awareness.
Despite these well-established findings, there has been little concern with the precise mechanism underlying the olfactory elicitation of emotion - particularly in relation to the visual and auditory modalities. One reason for this gap in psychological investigation is that there are as yet no definitive answers to two fundamental questions that underlie any research effort in this area:

• What exactly are olfactory emotions, and how are they organized?
• How are emotion episodes elicited and differentiated?

The main aim of this project, funded by, and carried out in collaboration with Firmenich SA, is to develop a new measurement methodology to study the emotional effects of odours. Concretely, it is suggested that emotions produced by odours should be studied as (more or less conscious) feelings that integrate cognitive, physiological, motivational and expressive effects, which may be accounted for by widely varying production rules. This multicomponential approach will include a major focus on individual and cultural differences, as these seem to play an important role in the relation between olfaction and emotion. Based on the Component Process Model (CPM), the first phase of this project plans to

• identify the semantic space describing emotions elicited by olfactory stimuli
• investigate the effects of selected odours on appraisal processes and consequent emotional responses.

What exactly are odour-elicited emotions, and how are they organized?

To address systematically the complexity of labelling olfactorily elicited emotions, we propose to investigate which labels people use in everyday life to describe the feelings and autobiographical memories associated with odours. In a first step, we will ask participants to evaluate which terms are best suited to describe the feelings elicited by particular odours. This will enable us to explore the structure of the emotional space related to odour experience. We will then test the fit between a scale for odour-elicited emotions and a new set of judgements using a large set of odorant samples. Finally, we will compare this new model with traditional emotion models - such as discrete-emotion or dimensional models - in order to confirm the validity of a specific model for olfactory emotion elicitation.

How are emotion episodes elicited and differentiated?

The CPM assumes appraisal-driven changes in different emotion components, including a complete set of predictions concerning which configurations of appraisal results will produce specific emotions and response patterns. In addition, the group that will collaborate with Firmenich SA has provided evidence for the direct effect of appraisals on specific physiological responses and on facial and vocal expression, and has thereby empirically confirmed critical predictions of the model. Several large cross-cultural studies have shown that appraisal patterns for specific emotions are fairly universal, although there are interesting cross-cultural differences in beliefs and values that influence appraisal outcomes.
Given that, in daily life, selective attention is usually not focused on ambient odours, most of our experiments will investigate the effects of incidental, rather than intentional, processing of odours. This experimental context should increase the ecological validity of the paradigms used. As individuals also explicitly evaluate odours (e.g., a consumer who wishes to buy a perfume), we are planning at least one experiment that will measure the effects of explicitly appraised odours.
We will conduct laboratory experiments to investigate the effects of odours on emotional processes by using

• behavioural recording
• subjective measures
• physiological recording
• brain imaging techniques.