Effects of age on American Sign Language sentence repetition.

The study of deaf users of signed languages, who often experience delays in primary language (L1) acquisition, permits a unique opportunity to examine the effects of aging on the processing of an L1 acquired under delayed or protracted development. A cohort of 107 congenitally deaf adult signers ages 45–85 years who were exposed to American Sign Language (ASL) either in infancy, early childhood, or late childhood were tested using an ASL sentence repetition test. Participants repeated 20 sentences that gradually increased in length and complexity. Logistic mixed-effects regression with the variables of chronological age (CA) and age of acquisition (AoA) was used to assess sentence repetition accuracy. Results showed that CA was a significant predictor, with increased age being associated with decreased likelihood to reproduce a sentence correctly (odds ratio [OR] = 0.56, p = .010). In addition, effects of AoA were observed. Relative to native deaf signers, those who acquired ASL in early childhood were less likely to successfully reproduce a sentence (OR = 0.42, p = .003), as were subjects who learned ASL in late childhood (OR = 0.27, p < .001). These data show that aging affects verbatim recall in deaf users of ASL and that the age of sign language acquisition has a significant and lasting effect on repetition ability, even after decades of sign language use. These data show evidence for life-span continuity of early life effects.