Dr. Wallace's Favorite Mental Models

Prospect Theory

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People don't weigh gains and losses the way simple math says they should. Prospect Theory describes how real decisions bend around a reference point, why losses sting more than equivalent gains feel good, and why small odds get over-weighted and near-certain odds get under-weighted.

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30-Second Understanding
Gains and losses aren't mirror images.

People evaluate outcomes relative to a reference point, not in absolute terms. A loss below that point hurts more than an equal-sized gain above it feels good, and the sting or thrill of each extra unit fades the further you move from the reference point.

Core question: What reference point is this decision being measured against, and is the choice being framed as a gain or a loss relative to it?

The shape of the value function

LOSS
GAIN

Losses (left of the gold line) are felt more steeply than same-sized gains (right of it) — the classic asymmetry behind loss aversion.

Mental Model Compass

Use it when a choice involves risk and framing.

The model is most useful when someone is choosing between options with uncertain outcomes, or when the same facts are being described in more than one way.

DecidePrimary use case
IntermediateDifficulty
4 minUnderstand
15–30 minApply with data
Risk & uncertaintyFramingBehavioral financeNegotiationPricing & marketingHealthcare decisions
Progressive Interactive Learning

Anchor → Frame → Weight → Reframe.

Walk through the same four moves analysts use to spot a framing or risk-preference pattern before acting on it.

01Anchor

Identify the reference point being used — the status quo, an expectation, a prior number, or someone else's outcome.

02Frame

Check whether the choice is being described as a gain above that point or a loss below it. The same facts can usually be framed either way.

03Weight

Look at how the probabilities involved are being treated. Are small odds being over-weighted, or near-certain odds being under-valued?

04Reframe

Re-describe the same facts around a different reference point or the opposite frame. If the preferred choice flips, the facts weren't driving the decision alone.

Diverse Worked Examples

The same pattern, six different rooms.

Open an example to see how reference points and framing show up in different kinds of work.

Investing
Holding losers, selling winners

An investor's reference point is usually the price they paid. A stock trading below that price feels like a loss to be avoided (so it gets held, hoping to "get back to even"), while a stock above it feels like a gain to be locked in (so it gets sold early). Researchers call this pattern the disposition effect, and it runs counter to tax and return-maximizing logic in many cases.

Marketing
Framing the same price two ways

"Save $10 if you pay by cash" and "pay a $10 surcharge for card" can describe an identical price difference. The surcharge framing presents the higher price as a loss relative to the reference point of the lower price, which tends to be felt more strongly than the discount framing presents the same gap as a gain.

Healthcare
Survival rates vs. mortality rates

Describing a treatment's outcome as "90% survival" versus "10% mortality" states the same statistic two ways. Studies of this kind of framing have found that patients and even physicians can choose differently depending on which frame they hear, even though the underlying numbers are identical.

HR & Negotiation
A number relative to last year's baseline

A compensation change framed as "reduced from last year's bonus" is anchored to a reference point that makes it feel like a loss, while the same dollar figure framed as "this year's new baseline" has no such reference point built in and tends to land very differently.

Insurance
Paying more than the math suggests

A low-probability, high-severity event (a house fire, a major illness) tends to get over-weighted relative to its actual likelihood, which is one reason people buy more insurance, and lower deductibles, than a strict expected-value calculation alone would recommend.

Product & Pricing
"You'll lose access" vs. "keep your plan"

A renewal reminder framed around losing an existing benefit tends to draw more attention than one framed around continuing to gain the same benefit, because the first anchors the reader's current access as the reference point and casts non-renewal as a loss from it.

Fully Worked Example

Two stocks. One of them has to be sold today.

This is an illustrative walkthrough designed to teach the method, built around the disposition-effect pattern described above.

Stock A: -15%
Stock B: +15%
SITUATIONNeed cash; must sell one of two stocks today
REFERENCE POINTOriginal purchase price of each stock
FRAMINGSelling A locks in a loss; selling B locks in a gain
PREDICTED PULLKeep A (avoid realizing the loss), sell B (bank the gain)
GOING-FORWARD FACTSBoth stocks have identical expected future returns from here
NEXTSeparate "how it feels" from "what the forward-looking numbers say"
Do not conclude: "The investor is irrational." The pull toward holding A and selling B is a predictable, well-documented pattern — not a personal failing. Naming it is what makes it possible to check the forward-looking numbers before acting on the feeling.
History & Accuracy

A psychology paper that reshaped economics.

Expand for the origin of the theory and what its 2002 Nobel recognition actually covered.

What did Kahneman and Tversky actually publish?

In 1979, psychologists Daniel Kahneman and Amos Tversky published "Prospect Theory: An Analysis of Decision under Risk" in the journal Econometrica. It proposed an alternative to expected-utility theory, built around a reference point, an S-shaped value function (concave for gains, convex for losses, steeper for losses than for gains), and a probability-weighting function describing how people treat stated odds.

What changed with Cumulative Prospect Theory?

In 1992, Tversky and Kahneman published a refinement, Cumulative Prospect Theory, which extended the original model to handle outcomes with many possible values and used a cumulative version of the probability-weighting function. It is the version typically used in later academic applications.

What did the 2002 Nobel Prize recognize?

Daniel Kahneman received the Nobel Memorial Prize in Economic Sciences in 2002 "for having integrated insights from psychological research into economic science, especially concerning human judgment and decision-making under uncertainty." Amos Tversky, Kahneman's longtime collaborator, had died in 1996; the Nobel is not awarded posthumously.

Is this the same thing as "Loss Aversion"?

No. Loss aversion — the finding that losses are felt more strongly than equivalent gains — is one component inside Prospect Theory's larger framework, alongside reference dependence, diminishing sensitivity, and probability weighting. Treating loss aversion as the whole theory misses the other three moving parts.

Common Mistakes

Simple-sounding does not mean simple to apply.

Treating the loss-aversion ratio as fixed

Figures like "losses feel about twice as bad as equivalent gains" are commonly cited approximations from the literature, not a universal constant. The actual ratio varies by person, stake size, and domain.

Collapsing the theory into loss aversion alone

Reference dependence and probability weighting are separate mechanisms. A framing effect can appear even when no loss is involved at all.

Assuming the reference point is always "now"

The reference point can be a past price, a competitor's offer, a promise, or someone else's outcome — not only the current state of affairs.

Using it to call someone irrational

The pattern is predictable and widely documented, not a personal flaw. The useful move is to name the pull, not to judge the person feeling it.

Ignoring that the effect can shrink

Expertise, repetition, higher stakes, and deliberate checking have all been shown to reduce framing effects in some settings. They are not immune to learning or incentives.

Using framing to mislead rather than clarify

The same tools that reveal a framing effect can be used to exploit one. Presenting a choice fairly, in more than one frame, is a different act than picking the frame most likely to manipulate a decision.

When Not to Use It

Some questions aren't about feeling.

Use expected-value math when...

stakes are small, probabilities are well known, and the choice repeats often enough that average outcomes matter more than the feel of any single one.

Use plain forecasting when...

you need to predict what will objectively happen, not why two equivalent descriptions of it are received differently.

Use ethical or legal judgment when...

the real question is whether an outcome is fair or permissible, not how strongly it is perceived as a gain or a loss.

Counterpoint: naming someone's reference point does not settle whether their underlying decision is wise. It explains the pull; it does not replace the judgment call.
Combine It With

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Try It Yourself

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Save as Skill

Turn this mental model into a reusable AI skill.

Save as Skill converts the model into portable Markdown instructions that teach an AI when and how to apply Prospect Theory, what questions to ask, what evidence to seek, what mistakes to avoid, and how to structure its analysis.

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Go Deeper

For readers who want the nuance.

Is the "losses feel twice as bad" ratio exact?

No. It is a commonly cited approximation drawn from the research literature, useful as a rough sense of scale. Measured loss-aversion ratios vary across studies, individuals, and the type of outcome involved, so it should be treated as an order-of-magnitude cue, not a formula to plug numbers into.

How is this different from Expected Utility Theory?

Expected Utility Theory, the older standard in economics, assumes people evaluate outcomes based on final wealth levels and weigh probabilities exactly as stated. Prospect Theory was built to explain documented patterns where real choices depart from that assumption — evaluating outcomes relative to a reference point rather than final wealth, and not weighting probabilities linearly.

Does probability weighting mean people are bad at arithmetic?

Not exactly. People can often state a probability correctly and still act on a different, distorted weight for it in a decision. The weighting function describes the gap between the stated probability and the psychological weight it carries in a choice, not a failure to do arithmetic.

Does framing always work, on everyone, every time?

No. Effect sizes vary, and some studies find framing effects shrink or disappear with higher stakes, repeated decisions, domain expertise, or when people are prompted to think it through carefully. Treat it as a well-documented tendency to check for, not an inevitable outcome.