What Is Behavioral Economics?
Written by Paweł Raja, PhD · Published · Updated
Definition
Behavioral economics is the study of how people actually make economic decisions — combining economics with psychology to explain when and why choices depart from the fully rational, self-interested behavior assumed in standard economic models.
Standard economics models people as homo economicus: perfectly informed, endlessly patient with arithmetic, consistent over time and interested only in their own payoff. Behavioral economics asks what happens when we replace that assumption with what experiments and field data show about real people — who have limited attention, rely on rules of thumb, care about fairness, and struggle with self-control.
The result is not a claim that people are irrational, but that their departures from the textbook are systematic and predictable. Because they are predictable, they can be modelled, measured and — through better design of choices — used to help people reach goals they already have.
Behavioral vs. traditional economics
| Assumption | Traditional economics | Behavioral economics |
|---|---|---|
| Rationality | Full: people optimise | Bounded: people use heuristics and shortcuts |
| Gains & losses | Only final wealth matters | Outcomes judged against a reference point; losses loom larger |
| Time | Consistent (exponential) discounting | Present bias: plans change when the future arrives |
| Information | Used fully and correctly | Limited attention; salient features overweighted; beliefs biased |
| Presentation | Irrelevant if the options are the same | Framing and defaults change choices |
| Motives | Self-interest | Also fairness, reciprocity, trust and social norms |
Core ideas
Most of the field's findings fall into five families. Each links to our full entries, with definitions, mechanisms, landmark studies and ways to counter them.
Risk & Loss
People evaluate outcomes as gains and losses from a reference point, and losses hurt more.
Loss Aversion · Mental Accounting · Sunk Cost Fallacy · Endowment Effect
Temporal Choice
People overweight the present, so plans made today are abandoned tomorrow.
Judgment & Belief
Mental shortcuts make beliefs and forecasts predictably biased.
Confirmation Bias · Availability Heuristic · Overconfidence Bias · Representativeness Heuristic · Base Rate Fallacy · Gambler's Fallacy · Hindsight Bias · Self-Serving Bias · Mere Exposure Effect · Halo Effect
Social Influence
What others do and think shapes what we choose.
Decision Architecture
How options are presented — defaults, order, number, salience — changes what people pick.
Default Effect · Anchoring Bias · Framing Effect · Choice Overload · Decoy Effect (Asymmetric Dominance) · Algorithm Aversion · Algorithm Appreciation · Salience Bias (Salience Theory) · Status Quo Bias · IKEA Effect
Nudges & choice architecture
The most visible application of behavioral economics is the nudge: a change in how a choice is presented that predictably alters behavior without banning options or materially changing incentives (Thaler & Sunstein, 2008). Whoever designs a form, a menu or a website is a choice architect, whether they intend to be or not.
Some well-documented examples, each with its study design and the result its authors report:
- Social-Norm Tax Reminder Letters: The HMRC Natural Field Experiments — Taxpayers paying within 23 days (Experiment Two): Standard reminder letter 33.6% → Letter + local & debt norm 38.6% (+5.0 pts) (Natural field experiment)
- Johnson & Goldstein Organ Donation Defaults: Opt-In vs. Opt-Out — Respondents agreeing to be organ donors (online experiment): Opt-in default 42% → Opt-out default 82% (+40.0 pts) (Online experiment)
- Opower Home Energy Reports: Neighbor Comparisons Cut Energy Use by 2% — Household energy use relative to the randomized control group: Households receiving reports: −2.0% vs. control households without reports (Natural field experiment)
- Save More Tomorrow (SMarT): Committing Future Pay Raises to Retirement Saving — Average saving rate of SMarT participants (% of pay): Before joining SMarT 3.5% → After four pay raises (40 months) 13.6% (+10.1 pts) (Before–after (participants))
Read what a nudge is (types, ethics and evidence), see all nudge examples that worked, or browse the findings database.
A short history
- 1955Herbert Simon proposes 'bounded rationality': people have limited time, information and computing power, so they satisfice rather than optimise.
- 1974Amos Tversky and Daniel Kahneman publish 'Judgment under uncertainty: Heuristics and biases' in Science, introducing availability, representativeness and anchoring.
- 1979Kahneman and Tversky's prospect theory (Econometrica) describes reference-dependent choice and loss aversion.
- 1980Richard Thaler's 'Toward a positive theory of consumer choice' catalogues anomalies such as the endowment and sunk cost effects.
- 1997David Laibson's quasi-hyperbolic discounting model formalises present bias.
- 2002Daniel Kahneman shares the Nobel Memorial Prize in Economic Sciences (with experimental economist Vernon Smith).
- 2008Thaler and Cass Sunstein publish Nudge, popularising choice architecture.
- 2010The UK government creates the Behavioural Insights Team, the first government 'nudge unit'.
- 2017Richard Thaler receives the Nobel Memorial Prize for his contributions to behavioral economics.
- 2022Large-scale evaluations (DellaVigna & Linos) and meta-analyses spark a debate over how big nudge effects really are at scale.
Does it work? Evidence & critiques
Many core findings — loss aversion, present bias, default effects, anchoring — have replicated widely. But the field has also had to get more careful. When DellaVigna and Linos (2022) analysed every trial run by two US government nudge units, the average effect was about 1.4 percentage points, far below the average in published academic studies. A 2022 meta-analysis reported a small-to-medium average effect for choice-architecture interventions, and a reanalysis argued that much of it disappears after correcting for publication bias.
The current consensus is pragmatic: some interventions, especially defaults, are reliably powerful; many information-only nudges are small; and effects should be tested in context rather than assumed. Read the summaries of RCTs to Scale and The Effectiveness of Nudging, or our methodology for how we select evidence.
Where to go next
- The full list of cognitive biases (30 entries)
- The best behavioral economics books, ranked
- Landmark research papers, summarised
- Original essays on trust, belief updating and AI
Behavioral economics: frequently asked questions
What is behavioral economics in simple terms?
Behavioral economics studies how real people make decisions about money, health and everyday life. It uses insights from psychology to explain predictable 'mistakes' — such as procrastinating on saving or overreacting to losses — that standard economics, which assumes perfectly rational people, does not predict.
How is behavioral economics different from traditional economics?
Traditional (neoclassical) economics assumes people have stable preferences, process information perfectly and act in their own interest. Behavioral economics keeps the economic toolkit but relaxes these assumptions, modelling limited attention, biased beliefs, present bias, loss aversion and social preferences such as fairness and reciprocity.
Who is the father of behavioral economics?
Richard Thaler is often called the father of behavioral economics, and won the 2017 Nobel Memorial Prize for it. The psychologists Daniel Kahneman and Amos Tversky laid much of its foundation, and Herbert Simon's earlier work on bounded rationality was an important precursor.
What are examples of behavioral economics?
Automatic enrolment into pension plans (using the default effect), tax letters telling people that most of their neighbours pay on time (social proof), energy bills comparing your use with your neighbours', 'was/now' pricing (anchoring), and commitment savings accounts (present bias).
What is a nudge in behavioral economics?
A nudge, as defined by Thaler and Sunstein, is any aspect of how a choice is presented that predictably changes behavior without forbidding any option or significantly changing economic incentives — for example, making the healthy option the default or the easiest to reach.
Do nudges work?
Many do, but usually by less than early studies suggested. An analysis of 126 trials run by two US government nudge units found an average effect of about 1.4 percentage points — roughly a sixth of the average in published academic studies — though nudges are often cost-effective because they are cheap to deploy.
Is behavioral economics psychology or economics?
It is a field of economics that draws heavily on psychology. Its researchers mostly publish in economics journals and use economic models, experiments and field data, but the assumptions about human behavior come from psychological evidence.
What are the main criticisms of behavioral economics?
Critics point to replication failures for some well-known effects, smaller effects in the field than in the lab, publication bias, a long list of biases without a unifying theory, and ethical concerns about governments or firms steering choices.
Cite this page
Raja, P. (Ed.). (2026, 8 Oct 2026). What Is Behavioral Economics? Definition, Examples & History. Behavioral Economics Lab. https://www.behavioraleconomicslab.com/what-is-behavioral-economics