Up to 4% of People Can Hear Colors or Taste Words. Here's Why.

Up to 4% of people experience synaesthesia, a condition where the senses blend in unusual ways.

In synaesthesia, one sense can automatically trigger another, such as seeing colors for letters or hearing colors in sounds.

Common forms include grapheme-color synaesthesia, auditory-visual effects, and mirror-touch synaesthesia.

Researchers think the condition may reflect differences in how the brain connects sensory pathways or prunes synapses.