Comprehending Turkish sentences using word order, thematic roles, and case

A core aspect of sentence comprehension is assigning thematic roles such as agents and patients to nouns. Turkish, a flexible word order language with accusative case-marking, allows us to compare the relative effect of word order, case-marking, and thematic reversibility in sentence comprehension. We conducted two spoken language comprehension experiments to investigate the relationships among these factors. Native Turkish-speaking adults were faster and more accurate in comprehending sentences with default word order than those with scrambled word order; case-marked sentences than non-casemarked sentences; and sentences with thematically irreversible nouns than those with reversible nouns. The effect of word order depended on the reversibility of the nouns, and case-marking had little-to-no effect on comprehension when the nouns were thematically irreversible. Our results suggest that while Turkish speakers use multiple cues to map thematic roles onto nouns, there are diminishing returns of facilitation with each additional source of information. These results give support to race-based models of sentence comprehension