Cultural Differences in Effect Sizes of the Color-Word Stroop Test: A Meta-Analytic Study

The Color-Word Stroop test (CWST) measures executive functions and has been used worldwide in various psychology research areas. It is more difficult to name the colored ink when the name of the color word and its ink are mismatched than to name the color patch, in which case the color name interferes with the naming of the colored ink. This phenomenon is referred to as the Stroop effect. Cultural differences in the Stroop effect have been explored since the 1960s. However, the results are inconsistent; some studies reported a larger Stroop effect among East Asians than Westerners, while others reported the opposite. To integrate previous findings of the Stroop test, this study conducted a meta-analysis using data from 737 samples from 399 articles related to the CWST. The results of a meta-analysis showed that the effect sizes of the Stroop effect were not homogeneous, with larger effect sizes in Asia compared to North America and Europe based on the data of reaction times. These results suggest that people in Asia have difficulty inhibiting the irrelevant information of color names to the current task, color naming. In contrast, no regional difference was found for other behavioral measures (e.g., correct responses). Our findings suggest cultural differences and universality in the Stroop effect, and they depend on the experimental procedures and behavioral measures.