Traceless relatives: Agrammatic comprehension of relative clauses with resumptive pronouns

Individuals with agrammatic aphasia fail to interpret reversible movement-derived sentences. According to the Trace Deletion Hypothesis, this impairment in comprehension results from the deletion of traces of phrasal movement. In order to test this hypothesis, we compared object relatives with a trace to identical object relatives that are not derived by syntactic movement and do not include a trace, but rather include a resumptive pronoun at the position of the embedded object. Five Hebrew-speaking individuals with agrammatism and 5 matched controls participated in this study. Comprehension was assessed using a binary sentence–picture matching task of 120 reversible relative clauses per participant, 40 subject relatives, 40 object relatives, and 40 object relatives with a resumptive pronoun. The comprehension of subject relatives was significantly above chance, but the comprehension of both types of object relative was at chance. Importantly, the insertion of a resumptive pronoun at the position of the trace did not improve comprehension. The comprehension of object relatives with resumptive pronouns was at chance, and not different from the comprehension of object relatives with traces. Two modifications for the Trace Deletion Hypothesis are considered: a more general deficit in thematic role assignment over an intervening argument, or a deficit in the construction of CP that results in failure to make the syntactic relation between the relative head above CP, the operator in CP and the embedded pronoun or trace within the relative clause.