The development of the causative construction in Persian child language.

The acquisition of systematic patterns and exceptions in different languages can be readily examined using the causative construction. Persian allows four types of causative structures, including one productive multiword structure (i.e. the light verb construction). In this study, we examine the development of all four structures in Persian child speech between the ages of 1;11 and 6;7, in correspondence with their caregivers' speech. We define developmental stages based on dendrograms derived from variability clustering (Gries & Stoll, 2009). These stages are further substantiated by qualitative data, including overgeneralization errors and alternating structures. We find that Persian-speaking children learn to exploit two (i.e. lexical and light verb construction causatives) of the four constructions. They go from relying on lexical causatives to forming progressively constrained templates for the more complex light verb construction. This first study of the development of Persian causatives supports a usage-based account of verb-by-verb learning in child language development.