title: Pleasant and Unpleasant Odors Influence Hedonic Evaluations of Human Faces: An Event-Related Potential Study.
abstract: Odors can alter hedonic evaluations of human faces, but the neural mechanisms of such effects are poorly understood. The present study aimed to analyze the neural underpinning of odor-induced changes in evaluations of human faces in an odor-priming paradigm, using event-related potentials (ERPs). Healthy, young participants (N = 20) rated neutral faces presented after a 3 s pulse of a pleasant odor (jasmine), unpleasant odor (methylmercaptan), or no-odor control (clean air). Neutral faces presented in the pleasant odor condition were rated more pleasant than the same faces presented in the no-odor control condition, which in turn were rated more pleasant than faces in the unpleasant odor condition. Analysis of face-related potentials revealed four clusters of electrodes significantly affected by odor condition at specific time points during long-latency epochs (600-950 ms). In the 620-640 ms interval, two scalp-time clusters showed greater negative potential in the right parietal electrodes in response to faces in the pleasant odor condition, compared to those in the no-odor and unpleasant odor conditions. At 926 ms, face-related potentials showed greater positivity in response to faces in the pleasant and unpleasant odor conditions at the left and right lateral frontal-temporal electrodes, respectively. Our data shows that odor-induced shifts in evaluations of faces were associated with amplitude changes in the late (>600) and ultra-late (>900 ms) latency epochs. The observed amplitude changes during the ultra-late epoch are consistent with a left/right hemisphere bias towards pleasant/unpleasant odor effects. Odors alter evaluations of human faces, even when there is a temporal lag between presentation of odors and faces. Our results provide an initial understanding of the neural mechanisms underlying effects of odors on hedonic evaluations.
authors.affiliation: Department of Psychological Sciences, University of Liverpool Liverpool, UK.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Cook
authors.affiliation: Department of Psychological Sciences, University of Liverpool Liverpool, UK.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Fallon
authors.affiliation: Department of Psychological Sciences, University of Liverpool Liverpool, UK.
authors.forename: Hazel
authors.initials: H
authors.lastname: Wright
authors.affiliation: Department of Research and Development, Unilever Port Sunlight, UK.
authors.forename: Anna
authors.initials: A
authors.lastname: Thomas
authors.affiliation: Department of Research and Development, Unilever Vlaardingen, Netherlands.
authors.forename: Timo
authors.initials: T
authors.lastname: Giesbrecht
authors.affiliation: Department of Psychological Sciences, University of Liverpool Liverpool, UK.
authors.forename: Matt
authors.initials: M
authors.lastname: Field
authors.affiliation: Department of Psychological Sciences, University of Liverpool Liverpool, UK.
authors.forename: Andrej
authors.initials: A
authors.lastname: Stancak
keywords: evaluation; event-related-potential; faces; odors; perception