On children's uses of from, by and with in oblique noun phrases

This study was designed to follow up children's early spontaneous uses of from to mark oblique agents by giving 40 children (aged 2;5-6;1), and 10 adults, grammatical and ungrammatical sentences containing from, with, and by to imitate and to repair. As predicted, children's imitations and repairs showed that (a) 2-year-olds produce from for agents, and with for instruments in imitation; and (b) as children get older, they shift to by for agents in their repairs, and keep from to mark locative sources. These findings support the hypothesis that when children first try to express oblique agents, before acquisition of conventional by, they choose from for this purpose because agents, as instigators of actions, are conceived of as the source of the action and its result.