January is motivation month as many of us resolve to do better, especially to lose weight. Two behavior change resolutions come to mind, eat less and exercise more. Dieting aside, how do we sustain an exercise habit “after the thrill is gone?” Cognitive neuroscience provides one answer. We will wade out into the weeds for a moment and then come back to reality. The exercise mode of choice is the daily walk.
Sustaining the exercise response involves rewards. Given that most exercise including walking is perceived by the body as hard work, right away walking is negatively reinforced. Unfortunately for many of us, techniques that produce positive reinforcement have a short shelf life, i.e. walking with friends, nature walks, novelty, varied walking routes. Friends are unreliable; nature walks lose their novelty; and there are only so many ways to vary walking routes. Worse, early success in weight loss too quickly plateaus.
What does neuroscience say? Purposeful responses (such as a long walk) are tied to reward mechanisms by neurotransmitters called dopamine. The most prominent target for the dopamine stimulation is the ventral striatum (VS), one of the evolutionarily primitive regions of the brain. Some have called it the reward center of the brain. Using fMRI scanners, neuroscientists can measure how stimulation effects the ventral striatum, and since the VS wants to be stimulated, higher brain centers feel a sense of pleasure when the VS is positively stimulated. Not surprisingly, novelty is one very powerful VS stimulator. So is acquiring money.
The reason that most motivation programs fail is related to the goal of expectation and that is the problem in using novelty as the basis of a motivation system to sustain the habit of walking. Scientific studies using fMRI scanners have shown that when reward is entirely expected on the basis of the preceding cue, the neurons do not respond to the reward. In terms of novelty and walking, once we have seen the interesting sights a few times, the neurons stop exciting the ventral striatum; same with friends, same with varying the route. The brain says, “I don’t give a darn, I’ve seen that already.”
First, applaud the ones with a strong sense of intrinsic motivation. They can continue their walking program because it’s the right thing to do. But those folks are not the ones that are making New Year’s resolutions to lose weight. For the rest of us we need to develop a motivation system that keeps the ventral striatum happy. For me, it is the endless thrill of finding money left behind. In different amounts and in different places, it is always waiting to be found by the vigilant walker.