Synaesthesia is a rare phenomenon in which real sensory experiences evoke sensory experiences that are not directly caused by outside physical events.
For example, when a synaesthete hears a name, it can experience certain taste unique for this particular name. For a synaesthete person, ‘John’ could always taste as chocolate. In one common form of synaesthesia letters and digits are associated with a concurrent 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). The theory of ideasthesia is based on arguments for introducing a semantic component and on a proposal how the semantic system contributes to the phenomenon. The following figure illustrates the central role of concepts for the additional sensations in ideasthesia across different sensory modalities:
Studies – Empirical evidence
Immediate transfer of synesthesia to new graphemes: 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).
Learning a new graphical “language”: 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).
Swimming-style synesthesia: 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). The figure below shows stimuli used to prove objectively the existence of swimming-style-synesthesia using a Stroop task.
A TED Ed educational movie on ideasthesia:
A lecture on ideasthesia at SoundThinking conference (YouTube):
Mroczko-Wąsowicz, A., D. Nikolić (2014)
Semantic mechanisms may be responsible for developing synesthesia.
Frontiers in Human Neuroscience 8:509. doi: 10.3389/fnhum.2014.00509
Jürgens, U.M. and D. Nikolić (in press)
Synaesthesia as an Ideasthesia – cognitive implications.
In: Synesthesia – Learning and Creativity. Edited by J. Sinha. Proceedings from the conference Synesthesia and Children. Learning and Creativity, Ulm, May 2012. Synaisthesis, Luxembourg.
Mroczko-Wasowicz, A. and D. Nikolić (2013)
Coloured alphabets in bi-lingual synaesthetes.
The Oxford Handbook of Synaesthesia. 165-180.
Rothen N., D. Nikolić, U.M. Jürgens, A. Mroczko-Wąsowicz, J. Cock, and B. Meier (2013)
Psychophysiological evidence for the genuineness of swimming-style colour synaesthesia.
Consciousness and Cognition, 22(1):35-46.
Nikolić, D. (2009)
Is synaesthesia actually ideaestesia? An inquiry into the nature of the phenomenon.
Proceedings of the Third International Congress on Synaesthesia, Science & Art, Granada, Spain, April 26-29, 2009.
Nikolić, D., P. Lichti and W. Singer (2007)
Color-opponency in synesthetic experiences.
Psychological Science, 18(6):481-486.