Prospect Theory

Kahneman and Tversky's Nobel Prize-winning theory that people evaluate outcomes relative to a reference point (not in absolute terms), feel losses roughly twice as strongly as equivalent gains (loss aversion), and are risk-averse for gains but risk-seeking for losses. A person who gains $100 then loses $100 feels net negative despite being financially unchanged. This asymmetry explains why people hold losing investments too long (hoping to recover to the reference point), sell winners too early (locking in gains), and why the fear of losing $100 motivates more than the hope of gaining $100.

When to use it

When designing pricing, offers, or communications about change; when people's behavior around risk seems irrational (it's rational under prospect theory); when framing effects are important—how you present information changes how it's evaluated; when analyzing why people hold onto losing positions or sell winning ones prematurely.

How it can help

Design decisions, offers, and communications with prospect theory in mind. Framing matters enormously: a 90% success rate feels different than a 10% failure rate despite being identical. Losses loom larger than gains, so frame changes as gaining something rather than losing something when possible. In negotiations: understand that concessions feel like losses (which are weighted 2x) while gains feel like gains (weighted 1x)—so each concession you ask for costs the other side more psychologically than the equivalent gain you offer. Bundle losses, separate gains.