Present Bias: The Root Problem
David Laibson’s 1997 paper in the Quarterly Journal of Economics (“Golden eggs and hyperbolic discounting”) formalized the behavioral economics concept that explains why people reliably fail to follow through on their own plans: present bias.
Standard economic models assume consistent time preferences: if you prefer $100 today over $110 tomorrow, you should also prefer $100 in 30 days over $110 in 31 days. Laibson showed that humans don’t work this way. The “now vs. soon” trade-off is evaluated completely differently from the “future vs. slightly-later-future” trade-off. People are disproportionately impatient about the immediate present, willing to make sacrifices in the future that they would not make if “the future” were now.
This is why Sunday’s plan to work out Monday morning is abandoned on Monday morning, why ambitious project timelines approved in January produce deferrals in February, and why the email follow-up you intended to send today is perpetually deferred. The cold-state self makes plans; the hot-state self doesn’t execute them. They are, in practical terms, different actors with different preferences.
The Research on Deadlines
Ariely and Wertenbroch (2002) in Psychological Science tested commitment device effectiveness directly with MIT students completing three assignments. Students were randomly assigned to: evenly-spaced external deadlines, self-chosen deadlines (any spacing they preferred), or a single deadline at the end of the course.
The results: students with external deadlines performed best on assignment quality and course grade. Students with self-chosen deadlines did better than the single-deadline group, but those with full flexibility tended to cluster their deadlines near the end of the course, replicating the cramming pattern that external deadlines prevented. Given freedom, people gravitate toward the temporally convenient rather than the behaviorally optimal.
The caveat worth noting: while the deadline effects on performance were clear, commitment devices don’t always increase task completion rates in field experiments. The mechanism is most reliable when the commitment is genuinely binding: real consequences, not just stated intentions.
What Makes a Commitment Device Actually Work
Three design principles distinguish effective commitment devices from ineffective ones:
- Real consequences. A commitment is only as strong as the cost of breaking it. “I’ll work out tomorrow” is an intention, not a commitment device. Paying a personal trainer in advance who doesn’t refund no-shows is a commitment device. Telling a friend you’ll donate to a cause you dislike if you miss the workout is a commitment device. The consequence needs to be salient enough to compete with the in-the-moment preference to defect.
- Social accountability to a named person. Accountability to a specific, named individual is substantially stronger than accountability to a group or to yourself. The named person creates a concrete social consequence (disappointment, judgment, damaged trust) that vague accountability mechanisms don’t produce. A commitment to “be more responsive” is weak; a commitment to your assistant that you’ll reply to the four flagged emails before leaving is much stronger.
- Elimination of the alternative. The strongest commitment devices don’t just make defection costly. They make it structurally unavailable. Writing the check before the work is done (put the charity check in the envelope, give it to a friend, and tell them to mail it if you miss your deadline) eliminates the future decision to defect. Blocking website access during work hours eliminates the choice to browse.
A to-do list records intentions. A commitment device binds them. The difference is consequence. A to-do item with no deadline, no accountability, and no cost to deferral will be deferred whenever the present-bias moment arrives. Effective commitment devices attach a real cost (social, financial, or structural) to defection.