Are schematic diagrams valid visual representations of concepts? Evidence from mental imagery in online processing of English prepositions

Embodied imagery hypothesis proposes the activation of perceptual-motor systems during language processing. Previous studies primarily used concrete visual stimuli to investigate mental imagery in language processing by native speakers (NSs) and second language (L2) learners, but few studies employed schematic diagrams. The study aims to investigate mental imagery in processing prepositional phrases by English NSs and L2 learners. Using image-schematic diagrams as primes, we examine whether any mental imagery effect is modulated by target preposition (over, in), the abstractness of meaning (spatial, extended), and stimulus onset asynchrony (SOA; 1,040 ms, 2,040 ms). A total of 79 adult L2 learners and 100 NSs of English completed diagram–picture matching and semantic priming phrasal decision tasks. Results revealed interference effects on L2 processing of over phrases and under 2,040 ms SOA, but no such effects were observed in the NS group. The selective interference effects in L2 suggest different mental imagery patterns between L1 and L2 processing, and processing schematic diagram primes requires high cognitive demands, potentially leading to difficulties in integrating visual and linguistic information and making grammaticality judgments. The findings partially validate schematic diagrams as visual representations of concepts and suggest the need for further examination of schematic diagrams with varying degrees of complexity.