In the article the concept of synaesthesia as a perceptional phenomenon is introduced. The first part describes the basic manifestations and specifics of synaesthesia (automaticity, permanency, idiosyncrasy).
The second part pursues the question of emergence of synaesthesia and related theories of the human perception development ("neonatal synaesthesia", "cross-modal-transfer", "interactive specialization approach"). In the third part the so-called "linguistic synaesthesias", i.e. synaesthesias where the linguistic units act as inducers, are examined and it is shown how the research on synaesthesia can relate to the (psycho)linguistic research.
In the last part the upcoming Canadian-Czech research project and its main hypotheses are introduced.