Pupil size tracks the effects of global context and semantic ambiguity on word-meaning processing

Processing word meaning often appears effortless, yet the language systemfrequently encounters ambiguous input requiring appropriate context integration toallow comprehension. Understanding the mechanisms that enablecontext-to-meaning interaction poses a challenge for cognitive neuroscience. In ourstudy, we will focus on the issue of whether and how global semantic context caninfluence the meaning processing of single words in Spanish. We present threeexperiments (N=137) using behavioral and pupillometry measurements to discernthe contributions of context congruency and semantic ambiguity duringword-meaning processing. In our first set of experiments, we manipulated semanticcongruence between context and word meaning, introducing a global semanticcontext that immediately preceded an ambiguous target word in a word-associationtask. In a third experiment, we manipulated word ambiguity and semanticcongruence using a semantic judgment task. We found that global context increasesthe preference for related meanings, as well as reducing processing time and theassociated pupil dilation, suggesting a reduction in cognitive load. Interestingly, theglobal context effect on pupil size was greater for words with higher levels ofambiguity. Our study highlights the cognitive system's flexibility in accessing wordmeanings, tracking the neurocognitive resources that allow a more efficient wordcomprehension. In addition, these findings underscore pupil dilation as a marker forcognitive effort during word meaning processing.