fMRI evidence of working memory load in naturalistic language processing
Abstract: Working memory plays a critical role in prominent theories of human incremental language processing. Because the compete parse cannot be recognized from a partial string, working memory is thought to be used to store and update parse fragments. Although constructed-stimulus experiments have produced evidence for this hypothesis, these findings have failed to generalize to naturalistic settings. In addition, the language-specificity of any such memory systems is unknown. In this study, we explore a rich set of theory-driven memory costs as predictors of human brain responses (fMRI) to naturalistic story listening, using participant specific functional localization to identify a language responsive network and a “multiple demand” network thought to support domain general working memory. Results show memory costs as postulated by the dependency locality theory, but only in the language network. We argue that working memory is indeed involved in core language comprehension processes, but that the memory resources used are housed in the language system.