I wrote a few years ago about a 2007 study on news grazers, the folks who skim the news, surf the channels, pick up bits and pieces of information along the way but who don't spend a lot of quality time on any one channel. In that earlier study, grazers were younger, less informed, more likely to be men.
A 2011 study examines the same topic from a somewhat different perspective. Grazers (or switchers, as they called them, since it focuses on people who flip channel to channel) in the 2008 election tended to be those who were more interested in the election and was positively related to political knowledge.
Two very different portraits of a grazer. In part these differences can be explained by measurement approaches and in part by the dependent variables examined. In the earlier study, grazing was the dependent variable. In the latter study, it's an independent or moderating variable. And no doubt channel switching is a very specific behavioral concept while grazer in the earlier study is a bit more fuzzy and less television-specific.
I'm not sure what we can take from these two different results, other than a lesson in how we conceptualize and operationalize our variables can make all the difference in our results.