Person vs. locative agreement: Evidence from late learners and language emergence.

Sign languages are frequently described as having three verb classes. One, 'agreeing' verbs, indicates the person/number of its subject and object by modification of the beginning and ending locations of the verb. The second, 'spatial' verbs, makes a similar appearing modification of verb movement to represent the source and goal locations of the theme of a verb of motion. The third class, 'plain' verbs, is characterized as having neither of these types of modulations. A number of researchers have proposed accounts that collapse all of these types, or the person-agreeing and spatial verbs. Here we present evidence from late learners of American Sign Language and from the emergence of new sign languages that person agreement and locative agreement have a different status in these conditions, and we claim their analysis should be kept distinct, at least in certain ways.

The two-word stage: motivated by linguistic or cognitive constraints?

Child development researchers often discuss a "two-word" stage during language acquisition. However, there is still debate over whether the existence of this stage reflects primarily cognitive or linguistic constraints. Analyses of longitudinal data from two Deaf children, Mei and Cal, not exposed to an accessible first language (American Sign Language - ASL) until the age of 6 years, suggest that a linguistic constraint is observed when cognition is relatively spared. These older children acquiring a first language after delayed exposure exhibit aspects of a two-word stage of language development. Results from intelligence assessments, achievement tests, drawing tasks, and qualitative cognitive analyses show that Mei and Cal are at least of average intelligence and ability. However, results from language analyses clearly show differences from both age peers and younger native signers in the early two-word stage, providing new insights into the nature of this phase of language development.

Continuity and development in the acquisition of inversion in yes/no questions: dissociating movement and inflection.

This paper examines two- to five-year-old children's knowledge of inversion in English yes/no questions through a new experimental study. It challenges the view that the syntax for inversion develops slowly in child English and tests the hypothesis that grammatical competence for inversion is present from the earliest testable ages of the child's sentence production. The experimental design is based on the premise that a valid test of this hypothesis must dissociate from inversion various language-specific aspects of English grammar, including its inflectional system. An elicited imitation method was used to test parallel, lexically-matched declarative and question structures across several different verb types in a design which dissociated subject-auxiliary inversion from the English-specific realization of the inflectional/auxiliary system. Using this design, the results showed no significant difference in amount or type of children's errors between declarative (non-inverted) and question (inverted) sentences with modals or auxiliary be, but a significant difference for sentences with main verbs (requiring reconstruction of inflection through do-support) and copula be. The results from sentences with auxiliary be and those with modals indicate that knowledge of inversion is present throughout our very young sample and does not develop during this time. We argue that these results indicate that the grammar of inversion is present from the youngest ages tested. Our results also provide evidence of development relevant to the English-specific inflectional system. We conclude with a new developmental hypothesis: development in question formation occurs in integrating language-specific knowledge related to inflection with the principles of Universal Grammar which allow grammatical inversion.