Spared syntax and impaired spell-out: The case of prepositions

The objective of the study was to identify the factors that determine the preservation/impairment of prepositions in aphasia. Five parameters derived from previous research (Bennis et al., 1983, Friederici, 1982, Grodzinsky, 1988, Kean, 1977, Kean, 1979 and Kreindler and Mihãilescu, 1970) were examined in a sentence completion task and three types of grammaticality judgement tasks using four subcategories of prepositions with 18 preposition tokens in a large number of test sentences. Prepositions were found impaired in both Broca's and anomic aphasia. Most of the parameters could not account for the data, and some data were in the opposite direction to the predicted. No disproportionate impairments of meaningless prepositions were found and prepositions with syntactic function were best preserved in the majority of patients. Patients made predominately within-category substitution errors. The results are interpreted as evidence for preserved syntactic knowledge about prepositions. It is suggested that a deficit at the post syntactic level of (late) spell-out is the underlying reason for the preposition deficit.