5 ideas
Perception can arrive through one sense at a time rather than as an integrated stream. When the author attends to what he is hearing, what he is seeing drops away, and switching channels takes time. What looks like inattention or ignoring someone may be a mind locked onto a single input channel while the others go dark.
An object or scene may register first as isolated features, such as a color, a pattern, a sound or a shape. Only later, and with effort, are these assembled into a recognized thing with a name and a function. A person entering a room can be experienced first as the color of a shirt or the texture of a voice, so recognition is built rather than given.
A person who cannot speak or control deliberate movement may still have a full, reflective inner life. The barrier lies between intention and the body's output, not in comprehension or thinking. Judging intelligence from speech or voluntary action therefore systematically misreads non-speaking people.
Rocking, flapping and other repetitive motions can supply sensory feedback that tells a person where their body is and that it exists. Without that feedback, limbs and the body's edges can feel absent or disconnected. Suppressing these movements removes a tool for self-location and calm rather than simply correcting a bad habit.
Tito Mukhopadhyay grew up in India as a non-speaking autistic boy. His mother, Soma, persistently taught him to point to letters and then to write by hand, a practice that later developed into her Rapid Prompting Method. Through this written channel he composed books of poetry and essays describing an inner life that his silence and movements had concealed, which makes his case a test for any claim about what non-speaking people can think.