Do Valenced Odors and Trait Body Odor Disgust Affect Evaluation of Emotion in Dynamic Faces?

Abstract

Abstract:Disgust is a core emotion evolved to detect and avoid the ingestion of poisonous food as well as the contact with pathogens and other harmful agents. Previous research has shown that multisensory presentation of olfactory and visual information may strengthen the processing of disgust-relevant information. However, it is not known whether these findings extend to dynamic facial stimuli that changes from neutral to emotionally expressive, or if individual differences in trait body odor disgust may influence the processing of disgust-related information. In this pre-registered study, we tested whether a classification of dynamic facial expressions as happy or disgusted, and an emotional evaluation of these facial expressions, would be affected by individual differences in body odor disgust sensitivity (BODS), and by exposure to a sweat-like, negatively valenced odor (valeric acid), as compared to a soap-like, positively valenced odor (lilac essence) or a no-odor control. Using Bayesian hypothesis testing, we found evidence that odors do not affect recognition of emotion in dynamic faces even when BODS was used as moderator. However, an exploratory analysis suggested that an

Background odors affect behavior in a dot-probe task with emotionally expressive faces

“…We did not employ an optional stopping rule; the final sample size was determined pragmatically, by our limited time and resources. In a previous study investigating odor effects in dynamic faces on RTs, only 21 participants were enough for decisive Bayes factors (Syrjänen et al, 2017). We opted for a larger sample size in the present study to get a more precise estimate of the effect size.…”

“…Objective measures such as facial expression recognition speed have provided results that facial expressions are recognized faster in an unpleasant odor context (Syrjänen, Liuzza, Fischer, & Olofsson, 2017), indicating that unpleasant odors may increase arousal, benefitting behavioral speed. This fits within a behavioral immune system framework where disease cues, such as an unpleasant odor, causes increased vigilance to environmental cues (BIS; Schaller & Park, 2011).…”

An Overprotective Nose? Implicit Bias Is Positively Related to Individual Differences in Body Odor Disgust Sensitivity

“…First, the odors were presented constantly over the duration of an experimental block. This might have resulted in habituation (Smeets and Dijksterhuis, 2014) to the smell, and suppression of its effect, although similar studies in our lab has shown no evidence of habituation (Syrjänen et al, 2017(Syrjänen et al, , 2019. To confirm the null effect of odors (or to find evidence for its existence), further research is needed where odor cues are brief and paired with each target stimulus (as they are in a priming task) rather than serving as background odors.…”

“…Both versions of the IAT were administered under three different odor-conditions: unpleasant and sweat-like odor (valeric acid), pleasant and soap-like odor (lilac), and a no odor condition (clean cotton pad). In previous research, valeric acid has been used as human feet sweat-like odor (Anderson et al, 2003;Syrjänen et al, 2017). Both odors were diluted with an odorless mineral oil solution (Propylene glycol, 1.2-propanediol 99%, Sigma-Aldrich) in order to reach what equals a moderate intensity.…”

“…Both odors were diluted with an odorless mineral oil solution (Propylene glycol, 1.2-propanediol 99%, Sigma-Aldrich) in order to reach what equals a moderate intensity. Based on our previous psychophysical investigations, a 30% concentration corresponds to a moderate intensity for both odors (Syrjänen et al, 2017). Participants were exposed to odors via cotton pads placed in tube-shaped cotton bands, tied under their noses -a method that has proved efficient in previous studies (Syrjänen et al, 2017(Syrjänen et al, , 2019.…”