Semantic competition as the basis of stroop interference: Evidence from color-word matching tasks

A color-word matching task was used to investigate the basis of Stroop interference. Subjects were shown a pair of stimuli: an ink color (e.g., a red bar) and a colored word (e.g, RED printed in red or blue) and decided whether the two items had the same meaning (meaning decisions) or whether they had the same surface color (visual decisions). In Experiment I, the two stimuli were shown simultaneously, and conflicting visual information of the word (e.g., RED printed in blue, against a red bar) led to interference in meaning decisions, whereas conflicting verbal information (e.g., BLUE printed in red, against a red bar) produced no interference in visual decisions. In Experiment 2, as an increasing time interval was imposed between presentation of the color bar and the colored word, interference in meaning decisions diminished, whereas interference in visual decisions was established. These results suggest that semantic competition, not response competition is the major source of Stroop and Stroop-like interference.