Investigation of Sound-Gustatory Synesthesia in a Coffeehouse Setting Nicole Ashley V. Santos and Maria Teresa R. Pulido Department of Physics, Mapúa University, Intramuros, Manila City, 1002, Philippines Keywords: Psychophysics, Synesthesia, Surveys, Data Analysis. Abstract: Synesthesia is a perceptual phenomenon involving the stimulation of multiple senses. In this work, we determine the presence of sound-gustatory synesthesia by looking at the possible effects of background music on the perceived taste of a coffee-sugar mixture. We asked participants (N = 83) to listen to music while identifying the tastes they perceived drinking a coffee-sugar sample. Our results showed that sweetness was perceived more while listening to the “Slow” music, which is consistent with previous work. The perception of sourness also increased with the tempo of the music, consistent with work associating sourness with pitch. Interestingly, participants also perceived saltiness and sourness even though the ingredients did not contain ingredients with those tastes, which provides further evidence of sound influencing taste perception. This study has shown the presence of sound-gustatory synesthesia in a typical coffeehouse setting, introducing potential applications in psychophysics, food science, and other complex systems research. Our algorithm has also shown how quantitative tools can be used in a qualitative field such as psychological perception. We expect multisensory, interconnected technology in the Internet of Things to spread the experience of synesthesia within a population, with Big Data enabling researchers to detect and measure synesthesia much more accurately. 1 INTRODUCTION Humans make use of sensory information to determine environmental properties (Hillis, et al., 2002). Synesthesia is the simultaneous perception of two or more stimuli as one experience, even when the external stimulation of the additional perceived sense is absent (Colizoli, et al., 2013; van Campen, 2009). Only around two to four percent of a population have some form of synaesthesia, and its origins are not yet clearly determined (Brang and Ramachandran, 2011). However, with the arrival of multisensory technology and the interconnectedness of Big Data, we expect a proportional increase in the manifestation and detection of synaesthesia. In particular, flavor perception makes use of multisensory integration of all other human senses (Spence, 2015). Gustatory synaesthesia involves the automatic and consistent experience of tastes that are activated by non-taste related inducers (Colizoli, et al., 2013), such as music (sound- gustatory) and words (lexical-gustatory) (Gallace, at al., 2011; Bankieris and Simner, 2013). In a study by Mesz, Sigman and Trevisan (2012), “Sweetness” is associated with high pitched, consonant, slow, and soft music, “Bitterness” is associated with low pitch and continuous music, “Saltiness” is perceived more when the music have silences between notes, and “Sourness” is with high pitched, dissonant and fast music. Perceptual associations between taste and different aspects of sounds (pitch, timbre, interval, or tempo) can lead to predictions about the effects of musical pieces on gustatory perception (Knöferle and Spence, 2012; Crisinel and Spence, 2009). Sound-gustatory synesthesia has been initially investigated in terms of how pleasure, associated with sound in the form of music or noise, affects taste as well. With the music used as a component of sound, the experience of drinking beer was rated more enjoyable with music than when in silence (Reinoso Carvalho, et al., 2016). Meanwhile, gelati consumed while listening to liked and neutral music had positive scores, while gelati consumed while listening to disliked music had negative scores (Kantono, et al., 2016). Meanwhile, background noise has been shown to reduce the 294 Santos, N. and Pulido, M. Investigation of Sound-Gustatory Synesthesia in a Coffeehouse Setting. DOI: 10.5220/0007719502940298 In Proceedings of the 4th International Conference on Internet of Things, Big Data and Security (IoTBDS 2019), pages 294-298 ISBN: 978-989-758-369-8 Copyright c  2019 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved