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Determining who responds better to a computer- vs. human-delivered physical activity intervention: results from the community health advice by telephone (CHAT) trial

Eric B Hekler12*, Matthew P Buman12, Jennifer Otten1, Cynthia M Castro1, Lauren Grieco1, Bess Marcus3, Robert H Friedman4, Melissa A Napolitano5 and Abby C King1

Author Affiliations

1 School of Nutrition and Health Promotion, Arizona State University, 500 N. 3rd St, Phoenix, AZ 85004, USA

2 School of Medicine, Stanford University, Stanford, USA

3 Department of Family and Preventive Medicine, University of California, San Diego, CA, USA

4 School of Medicine, Boston University and Boston Medical Center, Boston, USA

5 George Washington University, Washington, DC, USA

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International Journal of Behavioral Nutrition and Physical Activity 2013, 10:109  doi:10.1186/1479-5868-10-109

Published: 22 September 2013



Little research has explored who responds better to an automated vs. human advisor for health behaviors in general, and for physical activity (PA) promotion in particular. The purpose of this study was to explore baseline factors (i.e., demographics, motivation, interpersonal style, and external resources) that moderate intervention efficacy delivered by either a human or automated advisor.


Data were from the CHAT Trial, a 12-month randomized controlled trial to increase PA among underactive older adults (full trial N = 218) via a human advisor or automated interactive voice response advisor. Trial results indicated significant increases in PA in both interventions by 12 months that were maintained at 18-months. Regression was used to explore moderation of the two interventions.


Results indicated amotivation (i.e., lack of intent in PA) moderated 12-month PA (d = 0.55, p < 0.01) and private self-consciousness (i.e., tendency to attune to one’s own inner thoughts and emotions) moderated 18-month PA (d = 0.34, p < 0.05) but a variety of other factors (e.g., demographics) did not (p > 0.12).


Results provide preliminary evidence for generating hypotheses about pathways for supporting later clinical decision-making with regard to the use of either human- vs. computer-delivered interventions for PA promotion.

Physical activity; Intervention; Moderation; Interactive voice response; Behavioral intervention technology system; Targeting