Introduction
Although the five senses of our body are anatomically separated, stimulus from different sensory modalities have always been associated together. This is also known as crossmodal correspondences. Unlike correspondences between other sensory modalities, researches on combinations between audition and taste have only been rapidly growing in the past few years because evidences show that it can actually help improve the design of food as well as dining experience. However, the idea of describing music in terms of gustatory stimulus has been known for quite some time and one common example is the term “dolce” which is normally used in musical scores to describe “sweet” style of musical phrasing. Other than that, composers such as Berlioz had also described the sound of the oboe as “small acid-sweet” (Berlioz, 1856; quoted in Mesz et al., 2011, p. 209; see also Baudelaire, 1857) while for Des Esseintes, a sensualist character in Huysmans’s Á rebours, he associated taste of dry curacao to the sound of clarinet and liqueur to the oboe (Huysmans, 1926; pp. 59–61).
One of the earliest studies on crossmodal correspondences between audition and taste is by Holt-Hansen (1968, 1976). Participants were asked to match pitch of a tone to two types of beer and results showed that both types of beer correspond to different tones. Some participants even reported a quasi-synaesthetic condition where perceived pitch and taste were thought to be in harmony. A subsequent attempt to replicate this experiment by Rudmin and Capelli (1983) also shown similar results however no participants experienced the quasi-synaesthetic condition. This may be due to the fact that sample sizes were quite small with 10 participants at most.
More recently, a simplified version of the Implicit Association Test was used by Crisinel and Spence (2009, 2010a, 2010b) to test the correspondence between pitch of music and basic taste sensations. Their results suggested that high pitch sounds correspond to sweet and sour taste, medium pitch to salty tastes while lower pitch links with bitter tastes. According to Spence (2012), this pitch – taste correspondence may originate from facial gestures a newborn makes when eating. In particular, when ingesting sweet tastes, their tongue goes up and out producing a higher pitch sound compared to when their tongue goes down during bitter taste. Addition to that, they also highlighted correspondence between taste and sound of music instruments where bitter and sour taste mapped onto trombone sounds and sweet onto piano sounds. This however raised the question where this difference may be due to difference in musical timbre as well as cultural associations for specific instruments.
Another study conducted by Reinoso Carvalho et al. (2015a) showed that when soundtracks that are congruent to a particular taste is played, participants will rate that particular taste higher. Moreover, Reinoso Carvalho et al. (2015b) also found out that customers are willing to pay more for a chocolate that has its own song. This is further supported by Spence et al. (2013, 2014) where participants perceived wine tasting sweeter when classical music is played as well as Areni and Kim (1993) showing that customers are willing to spend significantly more for wine when classical music is played. Meanwhile, an observational study done by Guéguen et al. (2008) linked higher amount of drinks ordered when music is played at 88dB, a much louder level compared to the normal 72dB. This might be the reason bars prefer loud music.
The purpose of this experiment is to find out whether different genres of music affects taste perception. Through previous evidences, we can conclude that playing music in the background enhances taste perception with pitch and loudness as a contributing factor as well. However, correspondence between genres of music and perception haven’t really progressing much. In this experiment, participants will be played extreme ends of music genre which we decided on classical and heavy metal music while rating strength of different tastes. Unlike other studies, we would also like to into account that favouritism towards a particular music can also affect the results therefore test will be given for participants to rate their likeliness towards the particular music. Here, we hypothesized that both genres of music will enhance and weaken different taste perception and likeliness may also have an effect on it.
Methods
Participants
Two hundred and ten participants (all of the participants must be at least 18 years of age) will take part in the experiment after giving their informed consent. Participants will be recruited through advertisements put out on the psychology experiment sites provided by University of Glasgow. Participants must have no sensory impairments during the period of experiment and a payment of £6/hr will be given for their participation.
Stimuli
Gustatory Stimuli
The taster will be given solutions of the five basic tastes which consist of sweetness, sourness, saltiness, bitterness and umami. The specific material which corresponds to the five basic tastes are sugar, vinegar, table salt, pure cocoa powder, and soy sauce. To make all these solutions the method of serial dilution is used. First, add 6 tablespoons of distilled water to a plastic cup and then add 10 grams of the specific material and stir until fully dissolved. This will make approximately 10 percent solution of a particular taste. Repeat the procedure to get 1 percent, 0.1 percent and 0.01 percent solutions. We will then taste all of these solutions by dipping a clean cotton swab into each solution and smearing it all around the tongue surface to find out the lowest concentration of each solution which can be tasted by our tongue. The suitable concentration solutions will then be used as our taste stimuli for the participants.
Auditory Stimuli
The two genres of music chosen are heavy metal and classical. “Pierce The Veil – King for a Day ft. Kellin Quinn” and “J.S. Bach – Prelude No.1“are the songs chosen corresponding to the genres respectively. Fragments of around 1 minute of the original songs (from min 1:40 to min 2:40 and min 1:00 to min 2:00 respectively) are played at 70 decibels using a speaker to the participants. By looking at the crossmodal correspondences between basic taste and sonic elements by Knoeferle and Spence (2012), it suggests that classical music might enhance perceived levels of sweetness due to the predominant piano and previous researches on effects of noise towards taste perception might suggest that heavy metal music may enhance umami perception.
Procedures
Firstly, participants will fill in a form on their personal details and accept the terms of the informed consent. The experiment has three different groups with different conditions. In condition A, participants are asked to evaluate the taste of five solutions in the presence of heavy metal music in the background. On the other hand, in condition B, participants will be played classical music and no music will be played in the background for condition C. Participants were divided into groups randomly and participants in condition A and B will be played both genres of music only in a counterbalance way (e.g a participant in the group with condition A will first listen to heavy metal music then classical and vice versa). However, participants in condition C will only be in the no music condition to provide a control measure.
We will be using the General Labelled Magnitude Scale (gLMS) to test the relative magnitude of the taste. Before the experiment starts, participants will be introduced how to use the gLMS. The gLMS is a psychometric scale with 100 units which are spaced to correspond to labels “barely”, “weak”, “moderate”, “strong”, “very strong”, and “strongest” (1, 5, 16, 34, 53, and 100 respectively). Participants will be using the gLMS brightness rating as a guide to making the rating of the taste. First, a medium- low light is shown and participants are to rate the brightness of this light. They will then be shown a medium- high light and we will ask if it is brighter or weaker compared to the previous light. Both ratings will then be marked on the scale. Lastly, a low, medium, and high light will be presented randomly and participants will be asked to mark these on the scale. During the taste test, participants will be asked to swish each solution in their mouth for maximum of 3 seconds and then spits it out before rating the strength of the taste. A bottle of water will be available for rinsing out their mouth before each taste test. At the end of the session, participants will also be asked to rate their likeliness of both songs using the 7-point Likert rating scales with 1 being “not at all” and 7 as “very much”.