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

Abstract

Background: 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.

Methods: 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: 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).

Conclusions: 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.

Figure 1

Amotivation moderating 12 month physical activity. Note: Results above are predicted values based on a multiple regression model that included arm (t = 0.11, df = 147, p = 0.91), amotivation (t = -1.2, df = 147, p = 0.24), baseline moderate- to vigorous-intensity physical activity (Mod+) (t = -7.0, df = 147, p < 0.0001), and arm X amotivation (t = 3.31, df = 147, p = 0.0012). Using standard conventions for modeling interaction effects, the y-axis represents the predicted value at 12 months of physical activity (i.e., kilocalories burned per kilogram per day that was in the moderate to vigorous intensity range) for those high and low in amotivation between the automated advisor and human advisor groups. Low Amot = One Standard deviation below mean for amotivation; High Amot = One standard deviation above the mean for amotivation.

Figure 2

Private self-consciousness moderating 18 month physical activity. Note: Results above are predicted values based on a multiple regression model that included Arm (t = 0.72, df = 147, p = 0.47), private self-consciousness (t = -1.02, df = 147, p = 0.31), residualized change score of physical activity from baseline to 12 months (t = 6.25, df = 147, p < 0.0001), and arm X private self-conscious (t = 2.04, df = 147, p < 0.05) predicting moderate- to vigorous-intensity physical activity (Mod+) at 18 months. Using standard conventions for modeling interaction effects, the y-axis represents the predicted value at 18 months of physical activity (i.e., kilocalories burned per kilogram per day that was in the moderate to vigorous intensity range) for those high and low in private self-consciousness between the automated advisor and human advisor groups. Low PSC = one Standard deviation below mean for private self-consciousness; High PSC = One standard deviation above the mean for private self-consciousness. This is based on previous conventions for graphing moderation analyses as described above.

Figure 3

Trend result of family social support moderating 18 month physical activity. Note: Results above are predicted values based on a multiple regression model that included Arm (t = 0.65, df = 147, p = 0.52), family social support (t = 0.86, df = 147, p = 0.39), residualized change score of physical activity from baseline to 12 months (t = 6.54, df = 147, p < 0.0001), and arm X family social support (t = 1.88, df = 147, p = 0.06) predicting moderate- to vigorous-intensity physical activity (Mod+) at 18 months. Using standard conventions for modeling interaction effects, the y-axis represents the predicted value at 18 months of physical activity (i.e., kilocalories burned per kilogram per day that was in the moderate to vigorous intensity range) for those high and low in social support at baseline between the automated advisor and human advisor groups. Low SS = one Standard deviation below mean for family social support; High SS = One standard deviation above the mean for family social support. This is based on previous conventions for graphing moderation analyses as described above.