Behavioral economics studies how real decision-making departs from the fully rational, fully informed optimization assumed in many baseline economic models, and what those departures imply for markets and policy.
What “behavioral” adds to standard models
A standard micro model assumes people maximize a stable utility function with correct beliefs and unlimited cognitive capacity. Behavioral economics relaxes those assumptions in (at least) two ways:
- Preferences can be reference-dependent: outcomes are evaluated as gains/losses relative to a reference point, not only in absolute levels.
- Choices can be noisy or biased: people may use heuristics, have limited attention, or make systematic errors even when incentives are clear.
The goal is not “people are irrational,” but “the frictions are structured enough to model.”
Core mechanisms and models
Prospect theory (decisions under risk)
Prospect theory captures two patterns often seen in experiments and in the field:
- Loss aversion: losses loom larger than gains.
- Probability weighting: people may overreact to small probabilities and underreact to moderate ones.
This helps explain behaviors such as insurance demand for rare events, or reluctance to realize losses.
Present bias (time inconsistency)
Many intertemporal decisions look like “I’ll start tomorrow” behavior. A common reduced-form representation is (\beta)-(\delta) discounting:
[ U_t = u(c_t) + \beta \sum_{k=1}^{\infty} \delta^k u(c_{t+k}), \quad 0<\delta<1, ; 0<\beta\le 1. ]
When (\beta<1), the agent is more impatient over the near term than over the long term, which can generate self-control problems (saving, debt, health investments).
Limited attention and salience
When information is complex or attention is scarce, choices may respond more to what is salient (fees, defaults, headline rates) than to what is economically equivalent but less visible.
Why it matters in economics
Behavioral frictions can change:
- demand and pricing: if consumers underweight add-on fees, firms may shift revenue toward shrouded charges,
- market dynamics: overreaction/underreaction can amplify volatility,
- policy design: taxes, disclosures, and defaults can have large effects even when they do not change feasible choice sets.
Practical example
Automatic enrollment in a retirement plan can raise participation dramatically, even when the opt-out cost is low. A standard model can rationalize this with small switching costs; a behavioral model can add inertia, limited attention, or present bias to match the magnitude of the effect.
Related Terms
- Bounded Rationality
- Prospect Theory
- Hyperbolic Discounting
- Time Inconsistency
- Expected Utility
- Rational Expectations