Dependency-Distance Effects Are Not Evidence Against Grammatical Theories With Empty Categories: When Psycholinguistic Data Are Not Diagnostic.

A long-standing question in cognitive science is whether psycholinguistic evidence can adjudicate among grammatical theories. This question arises in debates over the representation of linguistic dependencies: whether they are mediated by unpronounced elements (empty categories; ECs) or established without them. Some psycholinguistic research has taken dependency-distance effects-the observation that longer dependencies impose greater processing cost-as evidence in favor of EC-free over EC-mediated accounts, and this claim has recently been revived. In this letter, I argue that this conclusion is unwarranted. Once the incremental, real-time nature of sentence processing is taken into account, dependency-distance effects are expected under EC-mediated accounts as well. I show how EC-mediated accounts can explain these effects and review findings consistent with this view. Dependency-distance effects are, therefore, not diagnostic of whether dependencies involve ECs. More broadly, psycholinguistic data can be misleading when used to draw inferences about grammatical theories without reference to the real-time, incremental processes that give rise to those data.