In 2012, Gala Karina Villaseñor García tested how 123 Mexican university students understood replies to requests, for a master’s thesis at UNAM. Some replies came at once. Others came after a silence of 1.2 seconds.
The result: “un silencio antes de una respuesta negativa intensifica la noción de rechazo” (a silence before a negative answer intensifies the sense of refusal). The study also tested silence as the only reply.