Systemic functional grammar as a tool for experimental stimulus design: new appliable horizons in psycholinguistics and neurolinguistics

Since their onset more than 50 years ago, both psycholinguistics and neurolinguistics have provided crucial breakthroughs for understanding the cognitive bases of language. Despite their major contributions, however, both fields have been undermined by a tradeoff between ecological validity (i.e., the degree to which tasks reflect the conditions of everyday communication) and experimental control (the manipulation of fine-grained variables, which is typically achieved by matching lists of decontextualized words and sentences). Specifically, most extant research sacrifices the former requisite in pursuit of the latter, or vice versa, but both are rarely met in combination. To overcome this problem, we have relied on Systemic Functional Linguistics (SFL) and designed a protocol for constructing carefully matched but fully naturalistic narratives usable in experimental settings. First, we describe the limitations of mainstream language experiments and their poor ecological validity. Second, we introduce an SFL-based protocol that allows constructing naturalistic stories that differ in one critical target variable while guaranteeing statistical comparability in multiple other factors. Third, we illustrate how the protocol has been successfully implemented in two groundbreaking studies exploring the links between biological motor systems and lexico-semantic processing. Finally, we discuss the potential gains springing from future collaborations between SFL and experimental language research.