Present Bias and Hyperbolic Discounting
Why the same one-day delay looms larger today than next month: preference reversals, β-δ models, and commitment devices.
Standard economics discounted the future exponentially, which implies time consistency: your preferences today about next month are the same preferences you will hold next month. People are not built that way. Ainslie (1975) and later Laibson (1997) formalized what behavior shows — discounting is closer to hyperbolic, with the immediate future discounted disproportionately hard. The signature is the preference reversal: most people take $100 today over $110 tomorrow, yet prefer $110 in 31 days over $100 in 30 — the same one-day wait, valued differently depending on which side of "now" it sits.
Laibson's quasi-hyperbolic β-δ model captures this with two parameters: δ for ordinary impatience and β < 1 as an extra discount on anything not immediate. Present bias explains a family of otherwise puzzling behaviors: gym members who pay monthly fees that exceed the pay-per-visit price yet rarely attend (DellaVigna and Malmendier, 2006), chronic undersaving despite employer matches, credit-card revolving at 20% interest, and procrastination generally. The pattern is systematic, not random — which is why it belongs to economics and not just to character.
The model's most useful prediction is that sophisticated present-biased people demand commitment devices: arrangements that restrict their own future choices. Ulysses binding himself to the mast is the classical case; modern versions include Christmas clubs, illiquid retirement contributions, StickK-style contracts with money forfeited on failure, and the SEED accounts studied by Ashraf, Karlan, and Yin (2006) in the Philippines, which roughly doubled to tripled savings among committed users after a year. Sophisticates bind themselves; naive present-biased people don't, and so keep rescheduling their own good intentions.
Present bias reframes self-control as a time-inconsistency problem rather than a moral one: the planner self and the doer self trade off, and institutions — deadlines, defaults, deposits — are the technology that arbitrates between them. Its interaction with loss aversion is direct: immediate costs are losses felt now, while immediate rewards are gains discounted least, an asymmetry every savings product and every New Year's resolution must fight.
Tags
behavioral economics decision making procrastination psychology