Causal Role for Visual Cortex in Processing Visual Semantics

This article reviewed previous studies testing for the causal or correlational relationship between modality-specific brain regions (e.g. motor cortex) and processing of corresponding perceptual-motor semantics. The proposed experiment aimed to investigate the functional role of visual cortex in understanding visual-associated words by studying the selective effect of transcranial direct current stimulation (tDCS) to primary visual cortex on response time (RT) to visual-associated words in lexical decision task. Participants will receive either sham or true anodal-tDCS, then perform the auditory lexical decision task to decide if the stimulus is a word in English or a pseudoword word. The experimental prediction was that compared to sham tDCS, anodal tDCS will affect the RTs with visual-associated word stimuli significantly more than to nonvisual-associated word stimuli. If the experimental prediction is supported, then this experiment would provide additional empirical evidence for the embodied simulation hypothesis, whilst establishing a causal role for visual cortex in visual semantic processing.