Sunday, July 3, 2011

The Temporal Shape of Behavior

Wayback Machine: I wrote this post in February 2010 and never finished it. I still think it's mildly interesting, so I'm tossing it up here as-is. The next class I'm taking - Intervention Design and Development to Reduce Health Disparities - I expect will take up the question of models of behavior change again. In the interim I (and my classes) have focused more on societal-level solutions to public health problems.

I just made up the terminology in the title of the post. I'm sure there's been thinking done on this question that I don't know about, probably in more than one field. And there's probably a real name for what I'm talking about! But for now -

Health behaviors vary widely in their "temporal shape," by which I mean things like duration, frequency, pattern, and schedule. For example, there are things like vaccination, which occur at most once or twice a year (for adults anyway). There are tests that should be done every few years or even just once a decade until you get past fifty or sixty. On the other end of the spectrum, there are behaviors like washing your hands or smoking, where the opportunity to do or abstain from the behavior presents itself multiple times each day. Healthy eating falls into this category - for food-secure people, each day presents multiple occasions of eating or choosing not to eat, as well as offering the choice between healthier and less-healthy foods. Exercise is an example where it runs the gamut, from multiple times per day for a few people, to never for others, with most people somewhere in between (it'd be interesting to see if that's a bell curve - I'd guess no). Some health behaviors are quite situational - for example, wearing sunscreen or taking other skin-safety measures (Although I think the actual recommendations are probably to wear sunscreen every day).  Or consider alcohol intake - this can run the gamut from frequent to infrequent, as well as varying on the magnitude axis - and you could even say its health value (positive/neutral or negative) switches somewhere in the middle.

The models of behavior that function on the individual level pay attention to an individual's thought processes or internal psychological states. Given the wide variety of temporal shapes of health behaviors, it seems we should be paying attention to the interaction of those characteristics with the models we're using. For example, take the Theory of Planned Behavior, which incorporates an individual's perception of the health outcomes of a behavior and their perception of the social norms regarding that behavior. For a frequently-repeated behavior such as eating, does the model describe the psychological state of a person immediately prior to or during eating on each occasion? Or does it describe a general state of mind, not in flux, that governs eating on any occasion?

The professor of my course has claimed that the Health Belief Model works quite well "on simple, one-time decisions such as vaccination." I'm curious to know more about that result and what other behaviors respond well to interventions based on that model. If they are all of that temporal shape, that can tell us something important about when to use and when not to use that theory.

These questions offer another lens through which to look at the Diffusion of Innovation theory.  At first blush, it is uninterested in the temporal shape of a behavior, since all that is required is that a behavior be contagious.  On the other hand, if a behavior occurs extremely sporadically, it's not going to be visible enough to catch on, even if it is the kind of thing where people are influenced by observing the actions of others.

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