Ideasthesia (sometimes spelt ideaesthesia) is not a type of synesthesia: it is actually an alternative name for synesthesia or perhaps a more adequate way of describing it. In accordance with this theory, rather than being an interaction between one sense and another, synesthesia consists of an interaction between a concept or idea and a sense. The term was proposed by the Croatian-German neuroscientist Danko Nikolić in 2009, who considered it could apply to synesthesia and also to some other mental processes. His theory suggests that for synesthesia to occur, meaning must always be extracted from the stimulus inducing it, and it is therefore basically a semantic phenomenon.
The term ideasthesia is created by changing the root of the word in its Greek etymology: whereas “synesthesia” means “a union of sensations”, “ideasthesia” means something like “ideas-sensations” or “sensing concepts”:
synesthesia = syn (union) + aisthesis (sensation)
ideasthesia = idea (idea or concept) + aisthesis (sensation)
It is easy to see that some forms of synesthesia clearly fit in with this definition: grapheme-colour, for example, where the learnt concept of letters triggers a visual sensation of colour. Another example would be lexical-gustatory, where the concept or idea of words when they are heard or read evokes a sensation of taste. Other types of synesthesia, such as auditory-tactile, have traditionally been considered purely “sense-to-sense”, i.e. an association between two sensory elements with little connection to a cognitive act, but in accordance with the theory of ideasthesia they too involve concepts and ideas: in this case, those that the brain perceives when it makes sense of sound and music. In any case, what it is important to realise about ideasthesia is that it doesn't just refer to some types of synesthesia: it is an important theory about the possible nature of all types of synesthesia. It suggests that our ideas and our senses are inextricably linked, so much so that one can't exist without the other.
Many more scientific studies are still needed to tell us exactly how synesthesia really works and whether it does so in accordance with the premises of the neuroscientist Nikolić, but there is a good chance that his proposal will ultimately pave the way for how we understand the phenomenon in future.
More information on all aspects, studies, videos etc. on the page on synesthesia/ideasthesia on Danko Nikolić’s website.
This is the original 2009 paper in which he coined the term.
This page last updated: 9 February 2026
I believe in some cases ideasthesia should be a separate type, or Conceptualized synesthesia, maybe? Maybe for some auditory-tactile is strictly sense-to-sense, but for me, if I think of a song and hear it in my mind, it will trigger the same tactile sensations, colors, and any other type that may be triggered by that song. I can easily remember a song triggers a certain color or feeling, but remembering it is just that, a memory. But again, if I think of the song and hear it in my mind, it’s just like I’m hearing it through my ears, and all the same senses are activated. Albeit, the intensity isn’t as great, but due to my focus and attention to the song in my head, the sensations are definitely there. So would that be ideasthesia? I feel like as an autistic, this may be something specific for me as it’s my understanding that our synesthesia tends to be more intricately connected? I’m just learning about all of this. I found out I have synesthesia two months ago at the age of 48, so I could be completely wrong! :D
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