Visual feedback and self-monitoring of sign language.

The perceptual loop theory of self-monitoring posits that auditory speech output is parsed by the comprehension system. For sign language, however, visual input from one's own signing is distinct from visual input received from another's signing. Two experiments investigated the role of visual feedback in the production of American Sign Language (ASL). Experiment 1 revealed that signers were poor at recognizing ASL signs when viewed as they would appear during self-produced signing. Experiment 2 showed that the absence or blurring of visual feedback did not affect production performance when deaf signers learned to reproduce signs from Russian Sign Language, and production performance of hearing non-signers was slightly worse with visual feedback. Signers may rely primarily on somatosensory feedback when monitoring language output, and if the perceptual loop theory is to be maintained, the comprehension system must be able to parse a somatosensory signal as well as an external perceptual signal for both sign and speech.