Tracking effects of age of sign language acquisition and phonology in American Sign Language sentence processing.

Processing sign language involves activation of phonological features of signs. Previous research provides evidence for effects of age of sign language acquisition as well as amount and type of phonological relatedness during processing of single signs, but it is unknown how these factors affect sentence-level sign processing. This paper presents a phonological priming eye tracking study of American Sign Language (ASL) processing, in which we systematically vary the degree and type of phonological relatedness in prime-target sign pairs embedded in ASL sentences. We tested degree of relatedness by using sign pairs sharing either one or two out of three phonological parameters. We tested type of relatedness by using signs that were phonologically related in all possible combinations of the parameters handshape, location, and movement. Participants were exposed to sign language either early (before the age of five years) or late (after the age of five years), allowing us to explore how age of sign language acquisition impacts activation of phonological features of signs. Late signers were more affected by the degree of relatedness than early signers; primes that shared any information with the target led to increased time to identify the target, regardless of the specific parameter(s) that overlapped. There was a high degree of variability for type of relatedness, but sign pairs that shared location were particularly salient. Group differences suggested varying sensitivities to phonological information in early and late signers. Our study emphasizes that phonological relatedness should be carefully controlled when examining sign processing in signers differing in their language backgrounds.