Reliance on semantic and structural heuristics in sentence comprehension across the lifespan

People sometimes misinterpret the sentences that they read. One possible reason suggested in the literature is a race between slow bottom-up algorithmic processing and "fast and frugal" top-down heuristic processing that serves to support fast-paced communication but sometimes results in incorrect representations. Heuristic processing can be both semantic, relying on world knowledge and semantic relations between words, and structural, relying on structural economy. Scattered experimental evidence suggests that reliance on heuristics may change from greater reliance on syntactic information in younger people to greater reliance on semantic information in older people. We tested whether the reliance on structural and semantic heuristics changes with age in 137 Russian-speaking adolescents, 135 young adults, and 77 older adults. In a self-paced reading task with comprehension questions, participants read unambiguous high- versus low-attachment sentences that were either semantically plausible or implausible: i.e., the syntactic structure either matched or contradicted the semantic relations between words. We found that the use of top-down heuristics in comprehension increased across the lifespan. Adolescents did not rely on structural heuristics, in contrast to young and older adults. At the same time, older adults relied on semantic heuristics more than young adults and adolescents. Importantly, we found that top-down heuristic processing was faster than bottom-up algorithmic processing: slower reading times were associated with greater accuracy specifically in implausible sentences.