Synaesthesia is a rare phenomenon in which real sensory experiences in one modality evoke sensory experiences in another modality. For example, when a synaesthete hears a name, it can experience certain taste that is unique for this particular name. Thus, for a synaesthete person, ‘John’ could always taste as chocolate. In one common form of synaesthesia letters and digits are associated with perception of color. This phenomenon is known as grapheme-color synaesthesia. The illustration shows grapheme-color associations for one synaesthete who volunteered as a participant in our study.
We have conducted a number of studies conjointly indicating that synesthesia is not a sensory-sensory phenomenon, as it has been largely held. Instead, this is a semantic-sensory phenomenon in which the meaning of the stimulus induces perception-like experiences. Hence, I proposed that a more accurate name for the phenomenon is ideaesthesia, which is Greek for “sensing concepts” (Nikolić, 2009)(in German, Ideasthesie).
In one study we have been able to use the theory of ideasthesia and make novel experimental predictions, which in turn enabled us to create novel synaesthetic associations. In has been known that associations in grapheme-color synaesthesia are acquired in early childhood and remain robust throughout the lifetime. Also, it was known that synesthetic associations can transfer to novel inducers in adulthood as one learns a second language that uses another writing system. However, it was not known how long this transfer takes. The theory of ideasthesia predicted that grapheme-color associations should transfer to novel graphemes very quickly, within minutes. And this is what we have proven experimentally. We created novel synaesthetic associations after only a 10-minute writing exercise (see the illustration). Most subjects experienced synesthetic associations immediately after learning a new Glagolitic grapheme (Mroczko et al., 2009). Also, these associations generalized to graphemes handwritten by another person. The fast learning process and the generalization suggest that synesthesia begins at the semantic level of representation with the activation of a certain concept (the inducer), which then, uniquely for the synesthetes, activates representations at the perceptual level (the concurrent).
In another recent study we could show also that the process of choosing the colors for novel synaesthetic associaitons involves semantic processes. When faced with a novel meaningful symbol, synaesthetes often assign a color to it by using similarity judgments to other symbols: Symbols with similar shapes tend to be associated with similar colors (Jürgens and Nikolić, 2012).
We also discovered a new type of synaestheisa, dubbed Swimming-Style Synaesthesia. Here, each swimming style is associated with another color. We could show that phenomenon is also a case of ideasthesia. It is the concept of a swimming style that elicits the synaesthetic experiences. This synaesthesia does not require the proprioceptive information that arrives to the brain from being engaged into performing a particular swimming style (Nikolić et al., 2011).