Does the corollary discharge provide the sensory content of inner speech? A preregistered direct replication and extension of Scott (2013)

The mental production of speech or "inner speech" is a remarkable and foundational ability in humans, involved in many activities such as reading, writing, planning, or remembering. Inner speech is generally accompanied by a subjective multisensory (mainly auditory) experience. However, the cognitive and neural processes leading to these sensory percepts remain poorly known. One prominent perspective is that the sensory content of inner speech would correspond to the predicted sensory consequences of inhibited speech acts. Scott (2013) provided experimental evidence suggesting that inner speech indeed involves the mental simulation of speech acts, as evidenced by sensory attenuation of the concomitant perception of external speech sounds. However, this study assessed silent speech, but not inner speech, which does not involve visible articulatory movements. The present work aims to replicate and extend this study to assess whether inner speech attenuates the perception of concomitant and congruent external speech sounds.