American Sign Language phonology

American Sign Language (ASL) and other sign languages are characterized by phonological processes analogous to those of spoken languages. Phonemes serve the same role between spoken and sign languages: the main difference is spoken language phonemes are based on sound and sign language phonemes are spatial and temporal. Research into phonotactics in ASL is ongoing, but literature has largely agreed upon the Symmetry and Dominance Conditions as phonotactic constraints. Allophones perform the same in ASL as they do in spoken languages, where different phonemes can cause free variation, or complementary and contrastive distribution. There is assimilation between phonemes depending on the context around the sign when it is being produced. The brain processes spoken and signed language the same in terms of the linguistic properties, however, there is differences in activation between the auditory and visual cortex for language perception.