Phonetic reduction and variation in American Sign Language: A quantitative study of sign lowering.

During normal sign language use, a signer's productions will often be reduced from the citation forms of signs. This study examines a form of phonetic reduction in American Sign Language, in which signs that are located at the forehead are lowered in space. In particular, we explore the effects of signing rate and phonetic environment on the lowering of specific ASL signs and on their phonetic variation along the other two movement axes. Movement data were captured as native signers produced utterances that were controlled for phonetic environment and signing rate. We found that all signers produced lowered forms as an effect of the phonetic factors that we manipulated. In addition, several rate-induced effects occurred, which we had not predicted. Results are discussed in relation to past research on variation in sign production and in speech.