Today I’m looking at synaesthesia, but more specifically lexical-gustatory synaesthesia in which certain phonemes (smallest unit of speech such as the /l/ sound in jelly) trigger specific tastes. For example, in Jamie Ward and Julia Simner’s (2003) report, Lexical-gustatory synaesthesia: linguistic and conceptual factors, a case study was done on a forty year old business man who reported tasting specific tastes in response to certain phonemes. In this case the man reported tasting cake when the phoneme /k/ was used in a word. Synaesthesia is thought to occur due to the crossing over or connection of neurons in certain areas of the brain that regulate and process senses. However, there are differing theories as to how this arises.
One idea is that certain neural connections linking sensory areas are not destroyed in infant stages of development as done in normal development. Synesthetes therefore link one sensation with another because connections are not destroyed. The second theory is that, rather than sensory areas in the brain being directly connected, they are connected through neural pathways in higher processing areas. For instance, instead of just hearing a phoneme and having just any taste sensation, it is the processing of the sequences of phoneme in the word used that links to specific learned schemas connected to the phonemes leading then toward a specific taste. Ward and Simner examined this in their case study.
Through documentation of tastes stimulated by specific words and phoneme triggers, Ward and Simner found that their data supported the latter of the two theories. The largest support comes from the idea that the subject’s tastes are specific for certain learned phoneme association rather than just random association of tastes to arbitrary phonemes. For example, as stated earlier, certain phonemes consistently trigger specific tastes such as the phoneme /k/ and the taste of cake. Also, the use of semantics in the sensory process is a strong argument for higher processing connections as food names exhibit their tastes (cabbage triggers the taste of cabbage). Much of this may be because certain patterns of phonemes can trigger specific tastes that have the same sequence of phonemes. So college, having the phoneme sequence /edg/ triggers the taste of sausage which also contains the phoneme sequence /edg/. These associations are done through higher processing which is learned throughout life, supporting a connection through higher processing areas of the brain rather than direct connection between sensory areas.
Although the idea of a direct connection between sensory areas from birth is not disproved by the study, it has supported that there is higher processing connections involved that have developed through learning. There is still much work in the field of synaesthesia, and with any luck, it will lead us to a better understanding of how our brains develop and process information. But despite all this, the best thing to do right now if you are not a lexical-gustatory synesthete is eat leftover turkey, potatoes (cheesy or mashed), and some pumpkin pie. Happy holidays.