Evidence of optional infinitive verbs in the spontaneous speech of Spanish-speaking children with SLI

• Interface Deficit is a comprehensive tense-related theoretical account of SLI.
• 21 monolingual Spanish-speaking children with SLI have severe problems with tense.
• It is possible to detect tense errors in Spanish SLI spontaneous production data.
• Verb finiteness is a promising clinical marker of SLI in Spanish.

The purpose of this study is to determine whether the occurrence of nonfinite verbs in the spontaneous speech of monolingual Spanish-speaking children with specific language impairment (SLI) distinguishes them from typically-developing children of the same age and to consider the Interface Deficit account of SLI, in contrast to other prominent accounts of the tense deficit, in light of current literature. To demonstrate that tense, a discourse-sensitive construction, is problematic for Spanish-speaking children with SLI, 42 monolingual Spanish-speaking children, 21 with SLI and 21 age-matched typically-developing children, were recorded for 20–35 min sessions of narrative speech, in Mexico City. The children's ages ranged from 58 to 76 months. Utterances were coded for compliance with obligatory context, defined as whether or not they agreed with plausibly associated subjects in the grammatical context. Our results show that children with SLI produced significantly more errors in verb finiteness, taking into account obligatory context, than did their typically-developing counterparts. We conclude that the type and frequency of finiteness errors produced by the children with SLI indicate that these children do indeed pass through an Extended Optional Infinitive (EOI) Stage. Our measure of obligatory context enables the identification of a bare stem, non-finite verb form, previously unidentified in spontaneous speech studies of Spanish-speaking children with SLI. Consequences of these findings for 3 prominent theories of SLI are discussed.