During Obama’s 2012 campaign, volunteers asked potential voters if they would sign a commitment to vote card with the president’s picture on it. Obama also has a section on his website called ‘Commit To Vote’ (http://www.barackobama.com/commit). These are informal and voluntary agreements, but the fact that the would-be voter has already made a commitment to vote increases the likelihood that they will follow through. There was even an email sent out featuring film star Jessica Alba asking voters to put their hands over their hearts and pledge their vote to Obama. These techniques work so well because people prefer to follow pre-existing attitudes, values and actions and to remain consistent with their past selves.
Greenwald et al (1987) contacted students by telephone and asked them to predict whether they would vote or register to vote in the next few days. Participants who were asked if they would vote all predicted that they would and subsequently voted with substantially greater probability than participants who were not asked for a prediction (86.7% of those asked voted compared to 61.5% of those who were not asked). The researchers concluded that asking people if they will perform a socially desirable action appears to actually increase their probability of carrying it out.
Greenwald, A. G., Carnot, C. G., Beach, R., & Young, B. (1987). Increasing voting behavior by asking people if they expect to vote. Journal of Applied Psychology, 72, 315-318.