Late Signers Research Articles

Are “late-signing” deaf children “mindblind”? Understanding goal directedness in imitation

Recent studies with “late-signing” deaf children (deaf children born into families in which no-one uses a sign language) have indicated that they have difficulty performing tasks that require them to reason about other people's false beliefs. However, virtually no research has so far investigated how far late signers’ difficulties with mental state understanding extend. This paper reports one study that uses an imitation paradigm to examine whether late signers may also have difficulty in interpreting other people's actions in terms of their goals. Both late-signing ( N = 15) and second generation “native-signing” deaf children ( N = 19) produced a pattern of responses to this task that indicates that they can and readily do view the actions of others as goal-directed. We conclude that this form of mental state understanding (generally seen as a precursor to understanding false beliefs) is intact in late-signing deaf children.

Signposts to development: theory of mind in deaf children.

Possession of a "theory of mind" (ToM)--as demonstrated by an understanding of the false beliefs of others--is fundamental in children's cognitive development. A key question for debate concerns the effect of language input on ToM. In this respect, comparisons of deaf native-signing children who are raised by deaf signing parents with deaf late-signing children who are raised by hearing parents provide a critical test. This article reports on two studies (N = 100 and N = 39) using "thought picture" measures of ToM that minimize verbal task-performance requirements. These studies demonstrated that even when factors such as syntax ability, mental age in spatial ability, and executive functioning were considered, deaf late signers still showed deficits in ToM understanding relative to deaf native signers or hearing controls. Even though the native signers were significantly younger than a sample of late signers matched for spatial mental age and scores on a test of receptive sign language ability, native signers outperformed late signers on pictorial ToM tasks. The results are discussed in terms of access to conversation and extralinguistic influences on development such as the presence of sibling relationships, and suggest that the expression of a ToM is the end result of social understanding mediated by early conversational experience.

Effects of age of acquisition on grammatical sensitivity: Evidence from on-line and off-line tasks

ABSTRACTAmerican Sign Language (ASL) provides a unique opportunity to investigate the effects of late exposure to a primary language on adult linguistic processing. In Experiment 1, a video sign-monitoring task was used to investigate the grammatical sensitivity of 11 native signers (exposed to ASL from birth) and 10 late signers (exposed to ASL at a mean age of 12 years) to errors in ASL verb agreement. The results indicated that native signers, but not late signers, were sensitive to errors in verb agreement. Experiment 2 utilized both sign monitoring and off-line grammaticality judgments. Sentences which contained errors in either verb agreement or temporal aspect were presented to 10 native signers, 10 early signers (exposed to ASL between the ages of 2 and 7), and 10 late signers (exposed to ASL between the ages of 10 and 20). The results indicated that native signers were sensitive to errors in both verb agreement and aspect, and that early and late signers were only sensitive to errors in aspect morphology. In the off-line grammaticality test, all three groups were equally able consciously to detect the grammatical errors. These findings suggest that late exposure to a primary language affects the on-line integration of verb agreement information within a sentence, but does not affect sensitivity to semantic distinctions encoded by aspect morphology.

Lexical Recognition in Sign Language: Effects of Phonetic Structure and Morphology

Two experiments are reported which investigate lexical recognition in American Sign Language (ASL). Exp. 1 examined identification of monomorphemic signs and investigated how the manipulation of phonological parameters affected sign identification. Over-all sign identification was much faster than what has been found for spoken language. The phonetic structure of sign (the simultaneous availability of Handshape and Location information) and the phonotactics of the ASL lexicon are argued to account for this difference. Exp. 2 compared the time course of recognition for monomorphemic and morphologically complex signs. ASL morphology is largely nonconcatenative which raises particularly interesting questions for word recognition. We found that morphologically complex signs had longer identification times than matched monomorphemic signs. Also, although roots and affixes are often articulated simultaneously in ASL, they were not identified simultaneously. Base forms of morphologically complex signs were identified initially followed by recognition of the morphological inflection. Finally, subjects with deaf parents (Native signers) were able to isolate signs faster than subjects with hearing parents (Late signers). This result suggests that early language experience can influence the initial stages of lexical access and sign identification.