Response times and response accuracy for odor localization and identification

Although significant progress has been made over the last decades, the chemical senses remain less well explored than vision or audition. One method to assess participants' ability to identify or localize odors consists in the application of dichotomous stimuli (e.g., left- and right-sided stimulation). In this study we aimed to explore localization and identification mechanisms by investigating whether response times and response accuracy were correlated, with the aim of establishing the pertinence of response times as an additional measure for assessment of the olfactory function (1). We further examined an advantage of the right nostril which has been reported in several publications (2). We delivered two mixed olfactory/trigeminal odors (benzaldehyde and eucalyptol) to one nostril at a time in a pseudorandomized order to 23 normosmic participants; the other nostril received an odor-free air puff. In half of the trials we asked the participants to detect the stimulated nostril; in the other half, they indicated which odor they had received. We recorded response accuracy and response times. Participants reached higher accuracy in odor identification than in localization, driven by benzaldehyde. For the stimulus eucalyptol exclusively, we observed that participants were faster to respond after stimulation of the right nostril than to the left nostril, in the localization task. Finally, response times were correlated with response accuracy in the identification task, but not in localization. Our findings suggest that odor identification is easier than odor localization. In addition, we find further support for an advantage of the right nostril over the left nostril. Moreover, the measurement of reaction times may supplement other techniques of the assessment of odor identification.