Children's interpretation of phrasal versus compound -er nominals in English

We present new evidence that children learning English are overly liberal in their interpretation of deverbal nominals such as sweeper of leaves. Such phrasal -er nominals with an of-PP complement can only refer to Agents (e.g., the one doing the sweeping, cf. Levin & Rappaport, 1988; Rappaport Hovav & Levin, 1992; Van Hout & Roeper, 1998). We found that children, however, readily allow Instrument readings (e.g., the broom the leaves are swept with). Our findings are in line with previous studies on deverbal nouns (Randall, 1982; Johnson, Bateman, Moore, Roeper & De Villiers, 1996), but are not compatible with Clark and Hecht’s (1982) proposal. Taken together these studies suggest that children are not yet sensitive to the syntax of argument structure mapping in derived nominals. Children’s syntactic representations do not differentiate phrasal and compound -er nominals, whereas those of the adults are essentially different. Thus children’s lexicon-syntax interface for derived nominals is not adult-like and they still need to learn subtle details of the syntax of argument structure when a verb is nominalized. Van Hout and Roeper (1998) account for the exclusive Agent interpretation of phrasal -er nominals by positing an extended VP inside it. One of the heads in this extended VP introduces an Agent argument, which, as it must be bound by a referent, gets linked to -er, hence the obligatory Agent reading. Compound -er nominals on the other hand do not involve an extended VP, and may freely refer to Agents and Instruments. How do children interpret phrasal -er nominals with of-complements (catcher of flies) as compared to compound nominals with an incorporated complement (fly catcher)? In two experiments, one using a truth-value-judgment task and the other a picture -selection task, we tested 35 English learners (4;0-6;5) and 15 adults on their interpretation of phrasal -er nominals and -er-compounds, presenting them with pictures of Agent and Instrument referents. If subjects apply the syntactic argument structure consequences of -er nominals with of-complements, they should reject these for Instrument pictures, and accept them only for Agents, while at the same time accept both Agents and Instruments for -er compounds. This was indeed the pattern in the adults’ results. The children, however, accepted both kinds of referents for both types of noun phrases, making no distinctions. We argue that none of the children’s -er nominals have an underlying extended VP structure. Instead both types of -er nominals have the same, simple nominal structure in which the verb incorporates into the -er noun and there are no restrictions on argument mapping. Thus, the interpretation of both kinds of -er nominals is free for children (Agent, Instrument), as it is not restricted by underlying syntactic structure. Children still need to acquire how derived nominals inherit the argument structure from the original verb and how the arguments are mapped onto nominal syntax. Only then will they discover that subtle, but highly abstract variations in nominal syntax may have major implications for interpretation.