Likelihood of attending to the color word modulates Stroop interference

Three experiments investigated whether the Stroop color-naming effect is modulated by the likelihood of a color word capturing visual attention. In Experiment 1, a bar or a neutral word was presented at fixation as a color carrier, along with a color word randomly appearing in either an achromatic color (white in the main experiment, gray in a follow-up) or purple. Reduction of the Stroop effect (known as Stroop dilution) occurred when the color word was achromatic but not (or to a lesser extent) when it was in purple. In Experiment 2, the color of the color word remained constant throughout trial blocks, and Stroop dilution was equally evident when the word was always in purple and when it was always in white. In Experiment 3, a color bar was presented as the color carrier with both a color word and a neutral word. In this case, the Stroop effect was larger when the color word appeared in purple, and smaller when the neutral word appeared in purple, than when neither word did. These results imply that the extent to which processing of a color word occurs is determined by the likelihood of the word capturing attention.