Non speakers and those with minimal speech were assumed to suffer from an intellectual deficit. This assumption comes from the belief that speech equates to intelligence. But this isn't based on any facts or academic research. There are many people who lack speech that are considered intelligent (Stephen Hawking, Hellen Keller, deaf and mute people). People with apraxia (mind-body disconnect) who have a hard time sitting still, moving their bodies intentionally, or responding to motor demands are as intelligent as anyone, but they lack the motor control for speech.