Amusics can imitate what they cannot discriminate.

A longstanding issue in psychology is the relationship between how we perceive the world and how we act upon it. Pitch deafness provides an interesting opportunity to test for the independence of perception and production abilities in the speech domain. We tested eight amusics and eight matched controls for their ability to perceive pitch shifts in sentences and to imitate those same sentences. Congenital amusics were impaired in their ability to discriminate, but not to imitate different intonations in speech. These findings support the idea that, when we hear a vocally-imitatable sound, our brains encode it in two distinct ways- an abstract code, which allows us to identify it and compare it to other sounds, and a vocal-motor code, which allows us to imitate it.