The Stroop congruency effect is more observable under a speed strategy than an accuracy strategy.

Naming the ink color of an incongruent color word (e.g., RED printed in green) usually takes longer than naming the ink color of a color bar. However, when the ink matches the word (e.g., RED printed in red), naming tends to be faster. These phenomena are known as the STroop interference effect and the Stroop congruency effect, respectively. Although the interference effect has been robust and reliable across studies, the congruency effect tends to be elusive. It was hypothesized that this variation in outcomes might be related to subjects' response strategy. The experiment conducted to test this hypothesis induced either a speed or an accuracy strategy in two separate groups of subjects. Significant interference effects were found for both groups and the magnitudes did not differ. At the same time, the congruency effect was observed in the speed group but not in the accuracy group. These results suggest that researchers who wish to observe and study the Stroop congruency and interference effects should place special emphasis on speed. Implications of the study for a model of the Stroop effect are also discussed.