Olfactory–gustatory simultaneity judgments: A preliminary study on the congruency‐dependent temporal window of multisensory binding

Abstract

Background: A greater congruency of audio and video expands the temporal binding window (TBW). A similar phenomenon may occur with a combination of odor and taste, which are the main components of flavor.Objective: TBW is defined as the temporal resolution of synchrony perception. The larger the TBW, the lower the resolution. We hypothesized that the more congruent the odor and taste, the lower the temporal resolution of synchrony perception. Methods:To examine this hypothesis, 10 female participants performed simultaneity judgment (SJ) tasks under congruent (soy sauce odor with saline) and incongruent (cherry tree leaf odor with saline) conditions and evaluated the congruency with saltiness for the two odors. In the SJ tasks, participants reported whether odor and taste were presented simultaneously or successively. We assumed a Gaussian distribution for the temporal distributions of the simultaneous response rates and calculated the approximations. In addition, we computed the half width at half height (HWHH) as an index of TBW based on the coefficient of approximation for the temporal distribution of the simultaneous response rates.Results: HWHH was significantly larger under congruent condition than under incongruent condition. In addition, congruency with saltiness had a significant moderate positive correlation with HWHH. Conclusion:The larger the HWHH, the lower the temporal resolution of synchrony perception, supporting the hypothesis. This study suggests that the width of TBW depends on the cross-modal congruency similar to the case for audio-visual SJs.However, methodological improvements, including a larger sample size and genderindependent recruitment of participants, are essential to enhance the reliability of the findings because some of the results did not provide sufficient ESs or power.

Conflict regulation in flavour perception

“…Retro-and orthonasal olfactory/taste pairs: congruency can facilitate neural and perceptual enhancements of subthreshold combinations of olfactory/taste stimuli (Dalton et al, 2000). Congruent olfactory/taste pairs (e.g., the smell of soy sauce paired with the taste of salt) reportedly have a larger temporal binding window than incongruent pairs (e.g., the smell of cherry tree leaf paired with the taste of salt) (Gotow & Kobayakawa, 2023), hence a higher chance of becoming integrated into a unified percept. Taste/odour congruency improves retronasal odour referral to the tongue (Lim & Johnson, 2011) and linearly increases odour referral to the mouth as well as subjects' pleasantness ratings of olfactory/taste pairs (here, chicken and citrus odorants with sweet/sour or salty/savoury tastants (Fondberg et al, 2018)).…”