Fig. 1: Fusion-induced recalibration.

a On the first day of the experiment, participants reported their perception of an unambiguous, auditory-only baba spoken by author AM, randomly intermixed with control syllables. On each of the next 14 days (McGurk exposure), participants reported their perception of AM’s baba paired with AM’s incongruent visual gaga, expected to induce the McGurk fusion percept of dada. Five repetitions were presented on each day, randomly intermixed with other stimuli. On Day 16, participants reported their perception of AM’s auditory-only baba, randomly intermixed with control syllables. b During McGurk exposure, half of the participants frequently reported the fusion percept of dada (fusion perceivers; one black circle per participant; n = 14 participants). The remaining participants (n = 14) did not experience the McGurk effect. Instead, they usually perceived baba, the auditory component of the McGurk stimulus (auditory perceivers; one gray circle per participant). In this plot and all subsequent plots, symbols are jittered along the horizontal axis to enhance visibility. c Fusion perceivers showed changes in perception of the auditory component of the McGurk stimulus (auditory-only baba) from the pre-test to the post-test. In the pre-test, perception was veridical (participants always perceived baba), but in the post-test, fusion perceivers often reported a non-veridical percept of dada. In contrast, auditory perceivers perceived baba veridically in both the pre-test and the post-test (zero dada reports). Only fusion perceivers showed a perceptual change, prompting the term fusion-induced recalibration.