Classification & Assessment in Psychiatry · Paper A
Synaesthesia
Synaesthesia matters on the exam because it is a benign sensory variant that superficially resembles a hallucinationSeeing, hearing, or otherwise sensing something that is not really there.Read more → but is neither a symptom nor a disorder. It occurs when stimulation of one sensory modality automatically and consistently triggers an experience in a second modality. For example, imagine someone who has seen the letter 'A' as red for as long as they can remember, every single time they see it. In practice, the key task is recognising synaesthesia as normal variation, not a psychiatric symptom needing treatment.
Synaesthesia is involuntary, it cannot be turned off, and consistent, the same trigger always produces the same experience over years. It is usually lifelong, present since childhood, and often familial, running in families. The person has full insightA person's awareness and understanding that they are unwell and need help.Read more → throughout: they know the coloured letters or musical tastes are a feature of their own perception, not something happening in the outside world. Take someone who tastes 'mint' every time they hear a particular piece of music, consistently since childhood, with a parent reporting the same experience. A careful history, asking whether the experience is lifelong, consistent, and free of distress, is what separates synaesthesia from a symptom needing further assessment.