Adults Can Be Trained to Acquire Synesthetic Experiences

Fourteen non-synesthetic adults completed a structured training regime — roughly 30-minute sessions of 4–5 adaptive memory and reading tasks, five days a week, for nine weeks — designed to reinforce 13 specific letter–color associations. They were compared against a control group on a battery of behavioral and physiological tests before and after.

• ▸After training, participants showed the standard behavioral and physiological markers of grapheme–color synesthesia, including synesthetic Stroop effects and skin-conductance (physiological) responses.
• ▸Crucially, most participants reported genuinely perceiving colors for black letters — inside and outside the lab — the subjective experience usually considered the hallmark of 'real' synesthetes.
• ▸The trained group also improved on a fluid-intelligence test by an average of about 12 IQ points relative to controls, a striking secondary effect the authors treat cautiously.

This is the core proof that synesthetic perception can be trained in adulthood through consistent, structured association practice — exactly the kind of short daily sessions Chromesthesia is built around. We apply the same principle to sound→color instead of letter→color.