Ketty Russeva

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Behavioral as well as electrophysiological evidence suggests that words are processed differently than pictures in a number of tasks. We used within-form comparisons in order to control for effects of differential accessibility to separate cognitive representations by picture and word stimuli. A "same"-"different" judgement task was employed which is known to modulate certain event-related potential (ERP) measures. The purpose of the study was to identify ERP variance components that reflect comparison decisions as a function of stimulus type. Sixteen adult subjects were tested in this study. Stimuli were printed names and drawings of twelve common objects. In half of the trials, a word was followed by a drawing (W-P trials). In the other half, the reverse order was used (P-W trials). In W-P trials, subjects decided on the identity between their internal image of the drawing that was named by the word and the drawing stimulus. In P-W trials, comparisons were made on the name of the depicted object. ERPs were collected to the second stimulus. Manual RT was also recorded. Average ERPs were submitted to a Principal Components Analysis (PCA) --Varimax Rotation procedure, followed by separate ANOVAs on the component scores.