Studies of pleasantness and unpleasantness in olfaction

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This research program will examine the special relationship between our sense of smell and our emotions. Odours can elicit mood shifts and evoke emotionally loaded memories. The main goal of this program is to examine several factors that influence our judgments about whether or not we like certain smells and how these emotive judgments are represented in our brains. In the first series of studies, odour mixtures made of varying proportions of a pleasant and an unpleasant smell will be used to determine whether our physiological responses (such as skin conductance) to odours correlate with their pleasantness and also what brain structures respond to increasing odour pleasantness. In the second series, I intend to further explore previous findings that we judge and respond to odours based not only on their physical characteristics but also on our beliefs about their source. For example, our perception of and physiological response to an odour will be very different depending on whether we believe it emanates from carrot juice or mouldy vegetables. Brain correlates of this phenomenon will be explored using electrophysiological and blood flow measures of brain activity. Finally, we know that when we become familiar with certain odours, our reaction to them diminishes: pleasant odours become less pleasant and unpleasant odours become less unpleasant. In the last series of experiments, several questions related to this phenomenon will be explored: Is this effect stronger in food than non-food odours? Is the effect long-lasting? Does it occur in the nose or in the brain? What brain structures are associated with this shift in judgment? This research program will help us understand what factors contribute to our emotional responses and how these responses are organized in our brains. These discoveries will advance the fields of psychology and neurophysiology, and the findings obtained in healthy participants will be used in the future to better understand how people with different types of emotional disturbances, such as depression, anxiety disorders, schizophrenia and autism, respond to emotionally provocative stimuli.