Our lives are becoming more and more sedentary. Most of us have jobs that are sedentary, and we spend more time in the car or in front of screens than ever before. To combat this, some people have started to try increase their daily step count. But it can be hard to stay motivated over time. So researchers set out to figure out how to best motivate people that are trying to increase their daily step count. They first compared setting a static goal, which is where there’s one step count goal that doesn’t change, to setting an adaptive goal, which is where the goal changes based on how active a person has recently been. They also compared giving cash rewards immediately after a person reaches a goal, to giving cash rewards months later for just participating in the study.
The researchers recruited 96 overweight and inactive adults and had them wear pedometers while they were awake and recorded their daily step counts at baseline for about 10 days. So from day 1 to day 10, individuals in all four groups instructed to not change their daily behaviors so the researchers could get a feel their usual routine. Now, on day 11 of the study, which was the beginning of the intervention phase all participants were sent an email that encouraged them to strive for an ultimate target of 10,000 steps per day on at least 5 days a week.
They were then randomized into four groups: an adaptive goal and immediate reward group, an adaptive goal and delayed reward group, a static goal and immediate reward group, and a static goal and delayed reward group. Individuals in each of these four groups were then monitored for an additional 110 days—a little under 4 months. For the two static groups, 10,000 steps a day remained the goal for the rest of the study. The adaptive goal groups, however, were given daily goals based on a person’s step counts for the last 9 days. More specifically, they took the step counts over the prior 9 days, ordered them lowest to highest, took the 4th highest step count, rounded that number up to the nearest 25 steps, and set that as the next day’s goal. As an example, if the past nine days step counts were 951; 1,256; 4,508; 4,563; 5,218; 6,235; 7,358; 9,563; and 10,200; then they took the 4th highest step count which is 6,235 and rounded up to the nearest 25 steps. In this case 6,250 steps was the next day’s step goal. In this way, they reset the daily goal each day for the people in the two adaptive goal groups. Now, for the two immediate reward groups, individuals got one point for everyday they completed the goal, and every time they earned five points they were sent a gift card worth $5. The delayed rewards group earned rewards for simply participating, that were nearly equivalent to the maximum rewards that the immediate rewards group could earn, but they didn’t receive the money until the end of the study.
So what happened? Well, on day 11, the two static goal groups, who were told to aim for 10,000 steps per day, increased their steps from a baseline of 7200 steps per day to about 9800 steps per day—an increase of 2600 steps per day. Meanwhile, the two adaptive goal groups who were told to aim for 10,000 steps per day but were given their own daily adaptive goal based on their recent data, increased from a baseline of 7600 steps per day to about 9700 steps per day—an increase of 2100 step per day. The difference between the two groups was not statistically significant. Walking a lot on that one day was great, but then over the next 110 days, all four groups slowly walked less and less. But here’s where it got really interesting. The two adaptive goal groups walked an average of 8 fewer steps per day, whereas the two static goal groups walked an average of 18 fewer steps per day. So that by the end of the study the people in the adaptive groups were walking about 1,000 extra steps per day compared to the people in the static groups.
Now, let’s look at results of the immediate rewards groups versus the delayed rewards groups. On day 11, when all groups were instructed to aim for an ultimate target of 10,000 steps per day, the immediate rewards groups, increased their steps from a baseline of 7800 steps per day to about 10600 steps per day—an increase of 2800 steps per day. Meanwhile, the two delayed rewards goal groups, increased from a baseline of 7000 steps per day to about 9000 steps per day—an increase of 2000 step per day. This difference between the two groups was statistically significant. Over the next 110 days, both the immediate rewards groups and the delayed rewards groups had a similar rate of decrease in steps. But since the immediate rewards group had more steps on day 11, those groups also ended with a 1400 steps per day advantage over the delayed rewards groups. When looking at all four groups together, it’s clear that the group that received the static goal and immediate rewards performed the best on day 11, while the adaptive goal and immediate rewards group performed the best by the end of the study on day 120.
So what does this study tell us? Well, it suggests that immediate rewards for completing short term goals are more motivating than delayed rewards for long term goals. So instead of saying something like, “if I lose 40 lbs over the next six months I’ll go on a cruise,” it may be more motivating to say something like, “for every week I stick to my diet and exercise plan, I’ll set away $50 that I can use for whatever I like”. In addition, static goals seem to be slightly more motivating at the beginning of a behavior change, but adaptive goals that account for recent performance have more lasting power.
Video credit: Osmosis from Elsevier (https://osmosis.org/)