Behavioral economics also studies how experiences are evaluated and how choices are structured. Kahneman's peak-end rule holds that people judge an experience based on how they felt at its most intense point and at its end, rather than on the sum or average of every moment. In colonoscopy experiments, patients rated a longer procedure with a gradually easing end as less painful than a shorter one with an abrupt ending, even though the shorter procedure produced less total discomfort. The IKEA effect, in which people place disproportionately high value on products they partially created regardless of objective quality, shows that labor invested in a good can inflate its perceived worth.
Choice architecture is the practice of designing the environment in which people make decisions, including the layout of options, defaults, and the presentation of information. Nudge theory, developed by Richard Thaler and Cass Sunstein, proposes that subtle changes in choice architecture can steer people toward better decisions without restricting freedom of choice, embodying the philosophy of libertarian paternalism: guiding people toward welfare-enhancing choices while preserving their freedom to choose otherwise. Setting default options is among the most powerful tools in this toolkit. Auto-enrollment in 401(k) plans dramatically boosts retirement savings by making "enrolled" the default, while countries with opt-out organ donation systems achieve far higher donation rates than opt-in countries. Thaler's "Save More Tomorrow" program combines multiple behavioral insights — it starts contribution increases in the future to overcome present bias, ties them to pay raises to avoid loss aversion, and uses auto-escalation to exploit inertia — and has been shown to dramatically boost retirement savings. Social proof is another effective nudge: messages like "9 out of 10 of your neighbors reduced their energy use" encourage conservation through conformity to perceived norms.
Choice architecture can also backfire. The decoy effect, or asymmetric dominance, shows that adding a third, clearly inferior option can make one of the original options appear more attractive by comparison, manipulating choices through context rather than substance. Choice overload demonstrates that too many options can paralyze decision-making; in Iyengar and Lepper's famous jam study, shoppers presented with 24 jams were less likely to purchase than those who saw only 6. Related time-preference biases shape long-term decisions: present bias gives disproportionate weight to immediate payoffs over future ones, fueling procrastination and under-saving for retirement. Hyperbolic discounting formalizes this by modeling discount rates that are higher for near-term delays and lower for delays further in the future, unlike the constant rate in exponential discounting. The result is time inconsistency — preferences change such that what is preferred at one point is no longer preferred later, even without new information. To overcome these tendencies, people use commitment devices such as automatic savings deductions or public goal announcements to lock themselves into future behavior.