In this seminar, I will present the current state of knowledge about anomalous perceptual experiences in synaesthesia (e.g. experiencing colours for letters, tastes for words) that links together various levels of understanding from genetics through to brain structure, cognition, and perceptual experiences.  Whereas other kinds of anomalous perceptual experiences (e.g. visual hallucinations in people going blind) are triggered via compensatory plasticity changes in the brain, due to unreliable sensory inputs, this is not the case in developmental forms of synaesthesia.  If anything, their perceptual abilities are atypically good (on objective measures) and, moreover, they subjectively report higher sensitivity/aversion to sensory stimuli.  The latter closely resembles a defining symptom of autism, and I present evidence that the two conditions are related.  Enhanced perceptual functioning is one of several cognitive features that appear to be enhanced in synaesthesia (the others include memory and mental imagery).  Finally, I will discuss why these anomalous experiences exist.  I will argue that they do not convey any new information about the world (and, hence, have limited functionality) but are, instead, an emergent property of other adaptive design features.  In effect, synaesthesia is not functional in itself but the underlying disposition towards developing synaesthesia may well be.

By: Shelley Jenkins
Last updated: Wednesday, 16 January 2019