Prospect theory — loss aversion (Kahneman & Tversky)

Losses loom larger than gains: the value function is steeper for losses, λ ≈ 2.25

The value function is defined over changes from a reference point (not absolute states), is concave for gains and convex for losses, and is steeper on the loss side — a loss hurts roughly 2–2.5× as much as an equal gain pleases (the estimated coefficient λ ≈ 2.25).

Coefficient form = one constant states an asymmetry. The single number carries the whole practical claim: framing a proposition as avoiding a loss pulls about twice as hard as the symmetric achieving a gain.

Transfer. This is the ground of delivery-craft P16 (framing) and the "cost of staying" move: "here's what you're losing by not being read correctly" outperforms "here's what you'd gain," for the same fact. Reference-dependence adds the second lever — you can move the felt value by moving the reference point the reader compares against, not just the outcome. Use loss-frames to spur action, gain-frames for aspiration; the asymmetry says loss usually wins on action.

Kin: illustrative-formulas · delivery-craft P16 (framing) · expectancy-disconfirmation (reference-dependence) · fomo-is-faith-in-the-other.

Source: Daniel Kahneman & Amos Tversky, 'Prospect Theory: An Analysis of Decision under Risk' (Econometrica, 1979); loss-aversion coefficient λ ≈ 2.25 estimated in Tversky & Kahneman, 'Advances in Prospect Theory: Cumulative Representation of Uncertainty' (Journal of Risk and Uncertainty, 1992)