The effect of time pressure and semantic relatedness in spoken word production: A topographic ERP study.

Speaking involves information-universal and information-specific systems, and it remains unknown about the influence of two systems in spoken word production. We manipulated time pressure (with and without) as an information-universal factor and the semantic relatedness between target names and distractor words (semantically related and unrelated) as an information-specific factor in the picture-word interference (PWI) task, while electrophysiological signals were measured concurrently. Naming latencies showed a significant semantic interference effect in the condition without time pressure but none in the condition with time pressure. Spatio-temporal segmentation analysis indicated that time pressure only prolonged the duration of Map 4 ranging from about 250-350 ms post picture presentation, and meanwhile shortened the duration of Map 5 starting around 350-520 ms. Within the framework of serial models, the two time periods were presumably associated with lexical selection and phonological encoding in spoken word production. Cluster-based permutation analysis revealed that semantic relatedness modulated ERPs around 320-360 ms after picture onset in the condition without time pressure, while 530-570 ms in the condition with time pressure. Our findings reveal that time pressure prolongs lexical selection and shortens phonological encoding. Furthermore, time pressure dynamically modulates whether semantically related distractors exceed a competition threshold to interfere with target word selection.