Synesthesia isn't just in your mind. The body reacts as if the colors were real.
Live Science • • health
Key Points:
- A new study published in eLife shows that people with grapheme-color synesthesia exhibit real physiological changes in their pupils, reacting to internally perceived colors as if they were seeing actual colors in the environment.
- Researchers measured pupil size in 16 synesthetes viewing gray numbers and found their pupils constricted for brighter synesthetic colors and dilated for darker ones, mirroring responses to real color stimuli.
- The timing of pupil responses suggests synesthetic color perception is involuntary and perceptual rather than a conscious or associative process, with brain networks processing internal and real colors similarly.
- Control groups without synesthesia did not show similar pupil responses, indicating that synesthetic color experiences are automatic and distinct from deliberate color imagination.
- While findings provide objective evidence for synesthetic perception, the study’s focus on grapheme-color synesthesia leaves open questions about whether these results apply to other synesthesia types.
