[…] schizophrenia characterized by marked psychomotor disturbance, which may include immobility ( stupor or catalepsy ), excessive motor activity, extreme negativism, mutism, echolalia
[medical-dictionary.thefreedictionary.com]
This can include echolalia (repeating what other people say) and echopraxia (mimicking the movements of other people).
[psycom.net]
(3) or more of the following must be present: catalepsy, waxy flexibility, stupor, agitation, mutism, extreme negativism, posturing, mannerisms, stereotypes, grimacing, echolalia
[uv.mx]