Lasting effects of the COVID-19 pandemic on language processing.

A central question in understanding human language is how people store, access, and comprehend words. The ongoing COVID-19 pandemic presented a natural experiment to investigate whether language comprehension can be changed in a lasting way by external experiences. We leveraged the sudden increase in the frequency of certain words (mask, isolation, lockdown) to investigate the effects of rapid contextual changes on word comprehension, measured over 10 months within the first year of the pandemic. Using the phonemic restoration paradigm, in which listeners are presented with ambiguous auditory input and report which word they hear, we conducted four online experiments with adult participants across the United States (combined N = 899). We find that the pandemic has reshaped language processing for the long term, changing how listeners process speech and what they expect from ambiguous input. These results show that abrupt changes in linguistic exposure can cause enduring changes to the language system.

Beyond input: Language learners produce novel relative clause types without exposure.

Syntax famously consists of abstract hierarchical representations, essentially instructions for combining words into larger units like sentences. Less famously, most theories of syntax also assume a higher level of abstract representation. Representations at this level comprise instructions for creating the hierarchical representations used to create sentences. To date, however there is no experimental evidence for this additional level of abstraction. Here, we explain why the existence of such representations would imply that, under certain circumstances, speakers should be able to produce structures they have never been exposed to, and we test this prediction directly. We ask: Given the right type of input, can speakers learn a syntactic structure without direct exposure? In particular, different types of relative clauses have different surface word orders. These may be represented in two ways: with many individual representations or one general representation. If the latter, then learning one type of relative clause amounts to learning all types. We teach participants a novel grammar for only some relative clause types (e.g., just subject relative clauses) and test their knowledge of other types (e.g., object relative clauses). Across experiments, participants consistently produced untrained types, implicating the existence of this higher level of abstract syntactic knowledge.

Shared syntax between comprehension and production: Multi-paradigm evidence that resumptive pronouns hinder comprehension.

Language comprehension and production are generally assumed to use the same representations, but resumption poses a problem for this view: This structure is regularly produced, but judged highly unacceptable. Production-based solutions to this paradox explain resumption in terms of processing pressures, whereas the Facilitation Hypothesis suggests resumption is produced to help listeners comprehend. Previous research purported to support the Facilitation Hypothesis did not test its keystone prediction: that resumption improves accuracy of interpretation. Here, we test this prediction directly, controlling for factors that previous work did not. Results show that resumption in fact hinders comprehension in the same sentences that native speakers produced, a finding which replicated across four high-powered experiments with varying paradigms: sentence-picture matching (N=300), self-paced reading (N=96), visual world eye-tracking (N=96), and multiple-choice comprehension question (N=150). These findings are consistent with production-based accounts, indicating that comprehension and production may indeed share representations, although our findings point toward a limit on the degree of overlap. Methodologically speaking, the findings highlight the importance of measuring interpretation when studying comprehension.