Reaction Time Inconsistency in a Spatial Stroop Task: Age-Related Differences Through Childhood and Adulthood

ABSTRACT

Age-related differences in inconsistency of reaction time (RT) across the life span were examined on a task with differing levels of demand on executive control. A total of 546 participants, aged 5 to 76 years, completed a spatial Stroop task that permitted observations under three conditions (congruent, incongruent, and neutral) according to the correspondence between the required response (based on stimulus direction) and stimulus location. An interference effect was observed across all ages. Analyses of neutral condition data replicated previous research demonstrating RT inconsistency follows a U-shaped developmental curve across the life span. The relationship between age and inconsistency, however, depended on condition: inconsistency in the congruent condition was higher than inconsistency in both the neutral and incongruent conditions across middle-aged groups. Reaction time inconsistency may reflect processing efficiency that is maximal in young adulthood and may also be sensitive to fluctuations in performance that reflect momentarily highly efficient responding.

ACKNOWLEDGMENTS

This work was supported in part by a grant from Canadian Institute of Health Research (CIHR) to D. Hultsch, E. Strauss & M. Hunter and by grants from the Natural Science and Engineering Research Council of Canada (NSERC) to E. Strauss, and D. Hultsch. We thank Zeev Cherniawsky, Drew Henderson, Andrew Moll, and Kyle Zimmerman for their assistance in data collection.

Notes

¹ Statistical tests of significance and proportions of variance explained are reported only for the first step in the analysis within which each predictor was entered. This is because, within such an analysis, vectors representing the lower-order trends no longer do so after those for higher-order trends have been included in the analysis.