Purpose: The purpose of this letter is to clarify the psycholinguistic underpinnings of the tense marker total and tense agreement productivity score and to extend the discussion of when composite diversity and productivity measures are best used. Conclusion: We encourage the use of composite diversity and productivity measures when assessing…

The purpose of this study was to determine if children acquire grammatical case as a unified system or in a piecemeal fashion. In English language acquisition, many children make developmental errors in marking case on subject position pronouns (e.g., "Me" do it, "Him" like it). It is unknown whether children who produce…

The Mandarin resultative verb compound (RVC; e.g., "tui dao" "push fall" and "pa shang" "climb ascend") encodes complex events composed of an initiating action and resulting activity or state. This study investigated when Mandarin-speaking children acquired this language-specific device. Specifically, we…

This article investigates the relationship between third person singular present tense agreement morphemes, copula "is" and verb-"s", at 2;00 and 2;03. Language samples from 60 children at 2;00 were analyzed for the productivity of copula "is" as measured by the number of different morphemes preceding "is"…

Purpose: This follow-up study examined whether a parent intervention that increased the diversity of lexical noun phrase subjects in parent input and accelerated children's sentence diversity (Hadley et al., 2017) had indirect benefits on tense/agreement (T/A) morphemes in parent input and children's spontaneous speech. Method: Differences in…

Purpose: The relatedness of tense morphemes in the language of children younger than 3 years of age is a matter of controversy. Generativist accounts predict that the morphemes will be related, whereas usage-based accounts predict the absence of relationships. This study focused on the increasing productivity of the 5 morphemes in the tense…

Purpose: The authors of this study investigated the validity of tense and agreement productivity (TAP) scoring in diverse sentence frames obtained during conversational language sampling as an alternative measure of finiteness for use with young children. Method: Longitudinal language samples were used to model TAP growth from 21 to 30 months of…

Purpose: Evidence for tense marking in child-directed speech varies both across languages (Guasti, 2002; Legate & Yang, 2007) and across speakers of a single language (Hadley, Rispoli, Fitzgerald, & Bahnsen, 2011). The purpose of this study was to understand how parent interaction styles and register use overlap with the tense-marking…

Purpose: Theories of morphosyntactic development must account for between-child differences in morphosyntactic growth rates. This study extends Legate and Yang's (2007) theoretically motivated cross-linguistic approach to determine if variation in properties of parent input accounts for differences in the growth of tense productivity. Method:…

Purpose: This study tests empirical predictions of a maturational model for the growth of tense in children younger than 36 months using a type-based productivity measure. Method: Caregiver-child language samples were collected from 20 typically developing children every 3 months from 21 to 33 months of age. Growth in the productivity of tense…