Broad versus narrow bandwidth measures of experienced automaticity for physical activity.

Objective: Physical activity is important for health, yet most young adults are insufficiently active. Physical activity is regulated in part, by habit, typically operationalised as automaticity. Little is known about the characteristics of automaticity, or whether broad bandwidth unidimensional measures of automaticity for physical activity are superior to narrower bandwidth multi- dimensional measures. Design: This secondary analysis ( N  = 238) investigated the nature of automaticity, and relations between the dimensions of automaticity, global automaticity, and physical activity. Main Outcome Measures: The structure of the Generic Multifaceted Automaticity Scale (GMAS) was examined by confirmatory factor analyses. Structural equation models were estimated to evaluate relations between automaticity (measured on the GMAS and the Self- Report Behavioral Automaticity Index, SRBAI) and device- measured activity. Results: The hypothesised 3- factor structure of the GMAS was rejected, in favour of a 2- factor solution. Lack of intention/control and efficiency were associated with global automaticity, but not physical activity. Global automaticity was associated with moderate to vigorous physical activity and daily steps, but not light physical activity. Conclusion: Multi- dimensional measures of automaticity may not provide a more nuanced understanding of automaticity when predicting overall physical activity.