Do those ‘we know whether you voted’ warnings actually work? An expert weighs in.

Update, Jan. 30, 2016: A voter in Iowa tweeted about receiving a mailer from the presidential campaign of Sen. Ted Cruz (R-Texas) that hopes to goad him into heading to caucus by sharing the voting records of people he knows. The Cruz campaign confirmed that it had sent the mailer.
Source: Do those ‘we know whether you voted’ warnings actually work? An expert weighs in.