Romke Rouw

Pupil size reveals the perceptual quality and effortless nature of synesthesia.

Elife August 4, 2026 Christoph Strauch, Casper Leenaars, Romke Rouw

Synesthesia describes cross-over processes that can generate 'extra' conscious percepts, such as seeing additional color when reading numbers. While existing research focuses on the mechanisms and effects of synesthetic associations, it often overlooks its most distinctive feature: unique sensory phenomenology. Here, we introduce pupillometry as an objective physiological measure of synesthetic...