Adaptation to invisible motion impairs the understanding of verb phrases.

The question of whether low-level perceptual processes are involved in language comprehension remains unclear. Here, we introduce a promising paradigm in which the role of motion perception in phrase understanding may be causally inferred without interpretational ambiguity. After participants had been adapted to either leftward or rightward drifting motion, resulting in the reduced responsiveness of motion neurons coding for the adapted direction, they were asked to indicate whether a subsequent verb phrase denoted leftward or rightward motion. When the adapting stimulus was blocked from visual awareness under continuous flash suppression, wherein only the influence of low-level perceptual processes existed, we found the response inhibition in the adapted direction across diverse verb phrases, indicating that desensitization of motion perception impaired the understanding of verb phrases. Our findings provide evidence for the functional relevance of motion perception to phrase understanding. However, when the adapting stimulus was consciously perceived, wherein both the influence of low-level perceptual processes and high-level cognitive processes coexisted but counteracted each other, we found different results for diverse verb phrases. Our findings highlight the importance of considering the influence of conscious awareness on how visual perception affects language comprehension. (PsycInfo Database Record (c) 2025 APA, all rights reserved).