Using the EZ-diffusion model to score a single-category implicit association test of physical activity

Objective: The Single-Category Implicit Association Test (SC-IAT) has been used as a method for assessing automatic evaluations of physical activity, but measurement artifact or consciously-held attitudes could be confounding the outcome scores of these measures. The objective of these two studies was to address these measurement concerns by testing the validity of a novel SC-IAT scoring technique. Design: Study 1 was a cross-sectional study, and study 2 was a prospective study. Method: In study 1, undergraduate students (. N=104) completed SC-IATs for physical activity, flowers, and sedentary behavior. In study 2, undergraduate students (. N=91) completed a SC-IAT for physical activity, self-reported affective and instrumental attitudes toward physical activity, physical activity intentions, and wore an accelerometer for two weeks. The EZ-diffusion model was used to decompose the SC-IAT into three process component scores including the information processing efficiency score. Results: In study 1, a series of structural equation model comparisons revealed that the information processing score did not share variability across distinct SC-IATs, suggesting it does not represent systematic measurement artifact. In study 2, the information processing efficiency score was shown to be unrelated to self-reported affective and instrumental attitudes toward physical activity, and positively related to physical activity behavior, above and beyond the traditional D-score of the SC-IAT. Conclusions: The information processing efficiency score is a valid measure of automatic evaluations of physical activity.