While news channel selection and political perspective are to some extent self-reinforcing, a new study indicates that just four extra minutes of Fox per week increases likelihood that you'll vote GOP by 0.9 percent. The same four minutes spent with MSNBC can tilt your vote Democrat by 0.7 percent.
Perhaps more interesting than this finding is how it was achieved. Researchers noticed that channel numbers for Fox and MSNBC, which vary nationwide, are assigned almost randomly. They also observed that viewers favor channels with lower numbers for the sake of convenience.
Thus, areas in which Fox had a lower channel number were more likely to be conservative. In regions where MSNBC had the lower number, viewers leaned left. Either way, people watch the channel which is most easily available and, over time, come to share its perspective.