The quantified self/self-tracking movement aims to give people the ability to track their health data and behaviors. For example, by wearing devices such as Fitbits to track exercise, and by entering information about stress levels, people will be better equipped to track trends in their health and well-being. The goal is that people will be able to use this information not just to show off their cool new gadgets, but to understand their health and improve it.
The question is, will giving people more information change their behavior? There are numerous reasons why people aren't engaging in healthy behaviors, for example, lack of knowledge, lack of access to people who can help them change, lack of willingness to change, lack of belief that they can change, and many others. Assuming people do have the drive to change their behavior and believe that they can do so, they still might not change it. Here's a research example to illustrate why:
I worked with a colleague to find out how methods of communicating information about medication side effects influence medication adherence. We told people about their risk for medication side effects using language commonly conveyed by pharmacists and doctors (for example, "there is a low risk that you will experience headaches, nausea, etc") and then asked them to estimate the likelihood that they would actually experience those side effects. "Low risk" typically meant that, compared to taking a placebo, approximately 3 out of 10,000 people who take the medication would report side effects. However, instead of recognizing what pharmacists and pharmaceutical companies intended them to realize, people actually interpreted low risk to mean that about 33 out of 100 people would experience side effects (or over 1000 times greater chance of side effects than intended)! This means they dramatically overestimated their risk of side effects from medication. We then looked at whether presenting side effect information verbally ("low risk") versus through numbers (<0.03%, or 3 out of 10,000) would affect their intention to take the medicine. We found that changing the communication format not only helped them to better understand their risk but also improved their willingness to take the medication.
This illustrates one example of how giving people information might not change their behavior, as they might not understand that information unless it is presented correctly. Information about side effects is given both to satisfy regulatory guidelines and to give patients/consumers more information. Risk of side effects from medication is typically "very low," meaning that other things in their lives are much more "risky." However, people misinterpreted the information about the side effects because it was not presented in a way that they could understand. Presentation of information is very important, and this feeds back into the quantified self movement where, in order to change behavior, we need to present information in a way that takes account of people's psychology.
Will the quantified self and big data movements get people to change behavior? The answer is maybe. It depends on whether the information is tailored to human psychology.