A McCain ad released today features a former Clinton delegate telling fellow Hillary supporters that she plans to vote for John McCain and it's okay for them to do so too.

Strategically, the TV spot looks to break what communication researchers call the "spiral of silence" phenomena, the tendency for a person to be less likely to voice an opinion on a topic if the individual feels that they are in the minority, for fear of reprisal or isolation from that majority. Derived in...