You Can Develop Desired Health Behaviors

Developing teeth-flossing habits with strategic intentions

Posted Oct 04, 2013

Flossing Teeth
How do we develop more healthy habits?

A new study published by Gaby Judah and Robert Aunger (Disease Control Department, London School of Hygiene and Tropical Medicine, UK) with Benjamin Gardner (Health Behaviour Research Centre, University College London, UK) revealed some important principles for developing a new, rather mundane health behavior – teeth flossing.

We would all like our health behaviors like teeth flossing to be “second nature.” Healthy habits are the foundation of healthy lives, yet good intentions always seem to lose against well-ingrained habits. In fact, this is particularly problematic for people who consider themselves procrastinators, as our research has shown that procrastination is related to poorer health partially due to fewer wellness behaviors and more treatment delay.

Robert Aunger, the third author on this particular study, has explored health habits in a number of previous studies.  For example, hand washing and teeth brushing have a strong habitual component, but few studies have examined how these habits are formed.

From my early studies of animal behavior and learning in the 1970’s, I know that habits are partially an issue of reinforcement and repetition of a behavior in response to a stimulus. However, there’s more to human goal pursuit and habit formation than that, as we also have to remember previous intentions to act. This prospective memory of previous intentions, the commitment to the intention (motivation), and linking new behaviors to existing routines are all important factors in establishing new habits.

So, for example, if 1) I can remember my previous intentions, 2) I’m motivated to act and 3) I strategically link my intended new behavior to some point or cue within an existing habitual behavior, then I’m more likely to succeed. In fact, this is pretty much what this group of researchers tested in their study around the intended new behavior of teeth flossing.

In their study of establishing a new teeth-flossing habit, 50 people (a student and community sample) were divided into two groups. Half of the participants were instructed to floss before brushing their teeth, half after. The researchers collected self-reports on flossing behavior daily as well as through 4-week and 8-month follow-up reports where they assessed flossing automaticity (how habitual it was).

Why Flossing?

As the authors note,

“Flossing is a preventative health behaviour, which removes plaque from areas that brushing cannot reach, thereby preventing cavities and gum disease, and potentially having more systemic health benefits. Flossing is most effective when performed daily, preferably in the evening to prevent bacteria build-up when asleep.  Flossing typically occurs in an unvarying context (the bathroom) and so may feasibly be prompted by a single once-daily cue. Flossing thus offers an ideal behaviour for purposive habit formation research” (p. 342, references removed).

Why a before and after brushing manipulation?

The theory behind this is more than I want to summarize here, at least not in detail. It’s known as Event Segmentation Theory, and in essence we can think of segments within events and the space between events (and events as being part of routines). In this case, showering and tooth brushing might all be part of a getting ready for bed routine, but there is a psychological space between the showering and tooth brushing events that is important. What this means is tooth brushing itself might serve as a good cue for teeth flossing, but when moving from showering to tooth brushing, the event cue is not as strong or effective. Given this, they hypothesized that the floss-after-brushing group may do better at establishing a habit.

I’m emphasizing this point, albeit in a summary, because I think it has important implications for our own intention setting in our lives. When we make those all-important implementation intentions that I have stressed many times in this blog and elsewhere in my writing, we could make them more effective if we choose situations within an existing relevant event as opposed to outside of a relevant event.

In this study, “Participants were guided in how to form an implementation intention using prior-action cues from their routines (e.g., ‘when I put down my toothbrush at night, I will floss my teeth’)” (p. 344). That’s much different from when I hang up my towel from my shower, I will floss my teeth. As you’ll see, this did make a difference in the study.

What did they find?

The baseline for flossing for both groups was very low at the start of the study with both groups reporting flossing about twice per month on average (actually a little less than this, but I’m rounding it up from 1.2 and 1.4 times per month because these averages don’t make a lot of sense, do they?). How much they flossed later and how much it became automatic (a habit) varied by a number of things.

Here’s a quick summary of what they found:

  • During the 28-day study, flossing was more frequent for participants who flossed more prior to the study (makes sense, right?—they were already flossing more often), had greater prospective memory ability (they were better at recalling their intention to floss each night) and who held more positive attitudes about flossing (they had more motivation to floss).
  • Interestingly, how much flossing behavior was exhibited during the 28-day study did not vary by the placement of the flossing cue—i.e., before or after tooth brushing—however, the strength of the later habit did (as you’ll see below).
  • Post-intervention habit was higher for participants who flossed more frequently following the intervention and prior to receiving the intervention, and who had more positive attitudes towards flossing.
  • At the 4-week follow-up, there was a tendency towards stronger habits among those who flossed after, rather than before, tooth-brushing.
  • At the 8-month follow-up, habits were stronger and flossing frequency was higher for participants who flossed after rather than before brushing.

What can we take from this study?

Placement of desired new health behavior within existing routines, may positively affect the likelihood of habit formation. When you make new implementation intentions, think about the event in which they might fit best, and use some cue within that event to signal action. In other words, with the basic format of an implementation intention as “In situation X, I will do behavior Y to achieve subgoal Z,” make “situation X” a specific action or situational cue that is part of an already habitual action you do that is related to this new behavior, if possible.

Of course, what we also learn here is that everything is a person and situation interaction. We’re more successful if the person variables such as prospective memory and motivation for the new intended health behavior are high, and this then interacts with how well we manipulate situational cues (although I should note that the statistical interactions in this study were not significant).

Another key lesson from this study is that habits may form more effectively when we use appropriate cues even when the short-term behavioral change is not so obvious. In this study, the participants between the two groups did not differ significantly on flossing behavior during the study (perhaps because they were paid to participate?), however the group who made the intention to floss after brushing did establish stronger flossing habits as demonstrated by automaticity scores in the 8-month follow up.  This is just another example of how complex human motivation and habit formation are, as this is not a predicted outcome from other theoretical perspectives.

As with all studies, more research is necessary, and I hope someone in my own research group will look at a replication of this work in relation to procrastination. In the meantime, I know I’ll think more about Event Segmentation Theory and how I might use habitual actions within existing events to leverage the formation of new healthy habits that I find difficult to establish. My dentist will be thrilled!


Judah, G., Gardner, B., & and Aunger, R. (2013). Forming a flossing habit: An exploratory study of the psychological determinants of habit formation. British Journal of Health Psychology, 18, 338–353.