Kevork Djansezian/Getty Images
Joe Cigliano stand sin the voting booth as he casts his ballot at Allesandro Elemantary School on March 5, 2013 in Boyle Heights area Los Angeles, California.
Why people fail to vote has been question studied for decades. One group of voting researchers even got the US Census bureau to include a question about voting in its surveys.
Michael Alvarez is a political science professor at Cal Tech, and he's part of the CalTech/MIT Voting Technology Project. They're the group that convinced the Census Bureau to ask that voting question.