a phenomenon in which activations of concepts (inducers) evoke perception-like experiences (concurrents). The name comes from Greek, “idea”+”aisthesis”, meaning sensing concepts or sensing ideas. The main reason for introducing the notion of ideaesthesia was the empirical evidence indicating that the related term synesthesia (i.e. union of senses) suggests incorrect explanation of a set of phenomena traditionally covered by this heading. “Syn”+”aesthesis” denoting “co-perceiving”, implies the association of two sensory elements with little connection to the cognitive level. However, most phenomena that have inadvertently been linked to synesthesia, in fact are induced by the semantic representations i.e., the meaning, of the stimulus  rather than by its sensory properties, as would be implied by the term synesthesia.
|This picture is used as a test to demonstrate that people may not attach sounds to shapes arbitrarily: American college undergraduates and Tamil speakers in India called the shape on the left "kiki" and the one on the right "bouba".|
The Kiki-Bouba Effect: A Case of Personification and Ideaesthesia
There are previous cases of synaesthesia where personality is attributed to numbers or letters. In our results, the word Kiki is overall happy, clever, small, thin, young, unpleasant, and nervous. The starshaped figure is overall clever, tall, small, slim, nervous, unpleasant, and upper-class. That is, the correspondence above all concerns the qualifying adjectives clever, unpleasant, and nervous, as well as the physical appearance small and thin. This brings us to the fat-thin effect. Cinema, literature, comics, and children's programmes are full of contrasting figures: Don Quixote and Sancho Panza, Laurel and Hardy (called the fat man and the skinny man in Spain), Asterix and Obelix, Tintin and Captain Haddock, Bert and Ernie (Epi and Blas in Spanish), or the Spanish comic about very naughty twin boys called Zipi (with fair hair) and Zape (with dark hair). Our main conclusion is that first names and last names are not entirely arbitrary. There is a correspondence between (rounded vs. angular) names and physical characteristics (fat vs. thin objects or persons) and concepts (foolish vs. intelligent, nice vs. unpleasant). The Kiki-Bouba effect is a semantic one.