She 'played/acted dumb' [=pretended to know or understand less than she really did] so we would assign her the easier tasks.
She thinks television is contributing to the 'dumbing down' of America.
Cutting training programs will 'dumb down' the American workforce.
(..) He often hands me the phone, you know why? He just forgets. So you're right. He doesn't really feel any empathy for me. But he's tall, strong, healthy, and not as dumb as you think. So for now, given my "condition" like you say... I don't give a damn about where he comes from and what he's done. (..)2011 The Intouchables