I believe that best ethnographic insights come not from questionnaires, but from observing people. A few weeks back, I saw this NYT article, "Calorie Postings Don't Change Habits, Study Finds", which explored if and how posting calories in fast food restaurants impacts people's choices of what to order.
The results showed that people made less healthy choices in spite of visible nutritional information (or, maybe because of it?). That is, before the labeling law took effect, fast food restaurant orders had a mean of 825 calories. After the info was posted everywhere, this mean climbed to 846.
Here's a more interesting part, however. The study found that about half the customers noticed the calorie counts, which were prominently posted on menu boards. About 28% of those who noticed them said the information influenced their ordering, and 9 out of 10 of those said that they had made healthier choices as a result.
But when the researchers checked receipts afterward, they found that people had, in fact, ordered slightly more calories than the typical customer had before the labeling law went into effect, in July 2008.
Really? I don't think that those people intentionally concealed the truth - I think that they simply scrambled to rationalize why they choose to disregard the nutritional information.
First, when faced with a choice: healthier and more expensive vs. less healthy and less expensive, people choose the latter. For study participants, buying food is a price-sensitive situation, and while they certainly notice any information added to the price, it does not affect the choice. It's simply not relevant.
Ok, so this explains why 50% of people reported they noticed calorie information. But why almost 28% of them said that they made healthier choices as a result?? Well, they either: a) truly believed that they made a healthier choice, all information notwithstanding or, b) because they simply adjusted their responses based on their assessment of the survey expectations. Simply, they offered what they deemed to be a desired response.
And this is why surveys suck more often than not.
(the image above is Windows 7 Whopper, sold in Japan).