Present Bias, explained.
Present bias gives an immediate reward extra weight relative to a delayed one, beyond the discounting applied between future rewards.
Why it happens
A preference can reverse when a planned choice becomes immediate. Someone may prefer a larger reward next month over a smaller one next week, yet choose the smaller reward when it is available now. That timing change is the key distinction.
Some preferences change when a reward becomes immediate. Planning ahead can favour patience even when the same wait feels unattractive in the moment.
Read the result
Compare today-versus-later choices with later-versus-even-later choices. Change the immediate premium separately from the general discount rate to see which part creates the reversal.
A worked example
A plan meets a tempting moment
On Sunday, you intend to work on a useful project on Tuesday rather than take a small distraction.
When Tuesday arrives, the distraction is immediate and the project's benefit remains delayed.
A change in timing can reverse the preference even if the project's underlying value has not changed.
OPTIONAL DEEPER DETAILGo deeper: inside the model
Inside this model
This quasi-hyperbolic model values an immediate reward at its face value and a reward t days away at beta × 0.99^t × amount. Shifting both rewards into the future applies beta to both.
Where this idea is useful
A practical use
A commitment made in advance can help protect a study plan from immediate entertainment. This model lets you inspect the preference reversal behind that intuition.
A common misconception
“Choosing an immediate reward always shows present bias.”
An immediate option may rationally be better because of urgency, uncertainty, or opportunity costs. The model isolates timing preferences under simplified conditions.
What this explanation leaves out
- The weights are chosen assumptions, not a measurement of a person. Real delay choices also depend on trust, need and uncertainty about receiving a reward.
Is present bias the same as impatience?
General impatience discounts later rewards. Present bias adds a special preference for now, which can create inconsistency between a future plan and the choice made when the moment arrives.
Would you make the same choice if both options were shifted equally far into the future?
Associated thinkers
Further reading
Explore the original research or the teaching reference behind this experiment.