Long dismissed as a product of overactive imaginations or a sign of mental illness, synesthesia has grudgingly come to be accepted by scientists in recent years as an actual phenomenon with a real neurological basis. Some researchers now believe it may yield valuable clues to how the brain is organized and how perception works.
Smilek and colleagues have identified two groups of synesthetes among those who associate letters and numbers with colors, he explained in a telephone interview. For individuals in one group, which Smilek calls “projector” synesthetes,…
