Behavioural Economics: Bounded Rationality and Biases in Decision Making
Behavioural economics challenges the traditional assumption that economic agents are perfectly rational, self-interested utility (or profit) maximisers with full information.
Before you start
Make sure you're comfortable with these topics first:
Method
- State the two ways behavioural economics departs from the traditional rational model: bounded rationality (limited ability to process all information) and bounded self-control (acting against one's own long-term interest despite knowing better).
- Learn a definition and one concrete example for each named bias: anchoring, availability bias, social or herd behaviour and the framing effect.
- Explain nudge theory: because default options and the way choices are framed influence decisions, governments and firms can nudge people towards a particular outcome by changing the default, e.g. automatic pension enrolment, without banning any option or changing financial incentives, called libertarian paternalism.
- Learn at least one real UK policy example of a nudge, e.g. automatic enrolment into workplace pensions, or placing healthier food at eye level in canteens.
- For an evaluation question, weigh a behavioural explanation against a traditional rational-choice explanation for the same piece of behaviour, and consider the practical and ethical limits of nudges.
- Apply the concepts to unfamiliar scenarios by first identifying which bias or nudge concept best matches the behaviour described, then explaining the mechanism in the agent's own words.
- Compare the cost and reliability of a nudge with a tax, ban or regulation as alternative policy tools when answering an evaluation question.
Worked example
A workplace pension scheme changes from 'opt-in', where employees must actively sign up, to 'opt-out', where employees are automatically enrolled unless they actively choose to leave. Enrolment rises from 35 percent of eligible employees to 88 percent, even though take-home pay and the financial terms of the pension are unchanged. Explain, using a named behavioural economics concept, why enrolment rose so sharply.
- Note what did not change: the financial incentive, contribution rates, tax relief and employer match, is identical under both systems, so a purely rational, fully-informed agent should reach the same decision either way.
- Identify what did change: only the default option switched, from not enrolled unless you act, to enrolled unless you act.
- Apply the relevant concept: this is the default or framing effect combined with inertia, a form of bounded rationality, since assessing the decision and acting on it has a time and effort cost, and people often procrastinate on decisions with long-term consequences.
- Name the policy tool: this is a nudge, changing the default rather than banning opting out or changing the financial reward, so it preserves freedom of choice, known as libertarian paternalism.
- Conclude: the rise from 35 to 88 percent shows the default option itself has a large behavioural effect on decisions, which the traditional rational model, where only the financial terms should matter, does not predict.
Practice questions
Try each question, then tap to reveal the answer.
Q1What is meant by 'bounded rationality'?Show answer
Answer: The idea that people have limited information, time and mental processing power, so they use mental short cuts (heuristics) rather than fully optimising every decision.
Q2What is 'bounded self-control'?Show answer
Answer: Acting against one's own long-term interest despite knowing what that interest is, e.g. delaying saving for retirement or overeating despite wanting to be healthier.
Q3Define anchoring, with an example.Show answer
Answer: Relying too heavily on the first piece of information seen when making a decision, e.g. judging a discounted price as a bargain because it is compared to a high 'original' price shown alongside it.
Q4What is a 'nudge'?Show answer
Answer: A change to how choices are presented or to the default option, designed to steer people toward a particular decision without removing any option or changing financial incentives.
Q5Give one real example of a nudge used in UK policy.Show answer
Answer: Automatic enrolment of employees into workplace pension schemes, with an opt-out rather than opt-in default.
Q6What is the framing effect?Show answer
Answer: The tendency for decisions to change depending on how the choice is presented, e.g. as a gain or as a loss, even when the underlying options are objectively identical.
Q7Give one criticism of using nudges as a policy tool.Show answer
Answer: Nudges can be less reliable or produce a smaller effect than a tax, ban or regulation, and some argue it is ethically questionable for the state to exploit known biases in citizens' decision making, even for beneficial ends.
Exam-style questions
Written in the style of a A Level Economics exam paper, with a full mark scheme.
Explain, using an example, what is meant by 'herd behaviour' in consumer decision making.
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Assess the case for using behavioural economics, rather than traditional economic theory, to explain and influence consumer decisions.
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See real A Level Economics past-paper questions, with official mark schemes →
Free printable worksheet
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