The Psychology of Money & Risk

The Psychology of Money & Risk

Standard economic models assume people are rational maximisers who make consistent decisions based on expected value calculations. Behavioural economics — the discipline that emerged from the work of Kahneman, Tversky, Thaler, and their collaborators — documents the systematic, predictable ways this assumption fails.

These failures are not random errors. They are patterns — which means understanding them protects you from their worst consequences and, in some contexts, allows you to anticipate them in others.

Prospect Theory: The Shape of Value

Kahneman and Tversky's key finding was that value is not experienced linearly or symmetrically. The value function has three properties:

1. Reference dependence: Outcomes are evaluated relative to a reference point, not in absolute terms. What matters is not whether you have $1,000 — it is whether you have more or less than what you had before, or what you expected to have.

2. Diminishing sensitivity: Both gains and losses feel progressively less intense as they move away from the reference point. The difference between gaining $100 and $200 feels larger than the difference between gaining $900 and $1,000, even though both are $100 increments.

3. Loss aversion: The value function is steeper on the loss side than the gain side. Losing $100 is more aversive than gaining $100 is pleasant. The ratio is approximately 2:1.

These three properties together explain an enormous range of observed behaviours that standard theory cannot:

• Selling winners and holding losers: Investors sell stocks that have gained (locking in the gain feels good) and hold stocks that have lost (selling realises the loss, which feels worse than the current paper loss). This is the economically irrational but psychologically predictable result of loss aversion and reference-point effects.

• Risk-seeking in the domain of losses: When facing a certain loss, people prefer a gamble that might avoid it entirely — even when the expected value is worse. Organisations in financial difficulty make increasingly risky decisions because the certain loss of the status quo is more aversive than the gamble.

• Risk-averse in the domain of gains: When facing a certain gain, people prefer to take it rather than gamble for a larger but uncertain one — even when the expected value favours the gamble. We lock in the good feeling.

Loss Aversion in Practice

Loss aversion is everywhere once you see it:

Negotiation: Framing the same concession as "avoiding a loss" versus "gaining a benefit" produces different response rates. "You'll lose your early-bird discount if you don't act now" is more compelling than "you'll gain the full price opportunity if you wait" — even though they describe the same situation.

Sunk cost fallacy: The tendency to continue investing in a failing project because of what has already been spent — rather than evaluating future costs and benefits from this point forward. Money already spent is gone regardless of the decision made now. But the loss aversion that would be triggered by "giving up" on the past investment makes walking away emotionally harder than staying, even when staying is economically irrational.

Status quo bias: The tendency to prefer the current state over alternatives, even when alternatives are objectively superior. Changing requires accepting the certain loss of the current arrangement, and that loss looms larger than the potential gain of the alternative.

Effort to prevent loss > effort to achieve equivalent gain: Organisations will fight harder to retain a customer generating $X than they will to acquire a new customer generating the same $X. The fight is asymmetric — as behavioural theory would predict.

Mental Accounting: Money Is Not Fungible in the Mind

Richard Thaler's mental accounting research demonstrated that people do not treat all money as equivalent — they create psychological accounts that carry different rules.

Windfall effects: Money obtained unexpectedly (tax refunds, bonuses, gifts) is spent differently than equivalent money earned through regular income. Windfalls are more likely to be spent on luxuries or experiences, regular income on necessities. From a rational perspective, a dollar is a dollar. Psychologically, dollars have character.

Integration and segregation: People prefer to receive bad news in batches (one big loss is better than several smaller ones) but good news separately (multiple small gains are more pleasurable than one equivalent gain). Prospect theory explains this through the diminishing sensitivity of the value function.

Silo effects in budgeting: The mental account created for "entertainment" spending can reach zero while the mental account for "household expenses" has funds. Moving money between accounts requires mental work that people resist — which is why people simultaneously hold high-interest debt and low-interest savings rather than paying down debt with savings.

The Endowment Effect and What to Do With It

The endowment effect predicts that once you own something — a stock, a role, a strategy, an opinion — you will overvalue it relative to its objective worth. This has significant implications:

• Exit decisions: Leaving a relationship, role, or investment you have held is harder than entering an equivalent alternative would be, purely because of ownership. Knowing this allows you to ask: "If I did not already own/hold this, would I acquire it at its current cost?"

• Negotiation: Your opening position carries endowment effect; you have already "owned" the outcome you proposed, which makes concession feel like loss. Skilled negotiators acknowledge this and pre-commit to their actual minimum before entering negotiation.

• Strategy: Organisations hold onto failing strategies far beyond rational justification. The strategy is "owned" — abandoning it triggers loss aversion. Pre-mortem exercises and explicit sunset criteria for strategies are structural tools that counteract this.

The general lesson of behavioural finance is not that people are stupid. It is that the evolved human mind was optimised for a world very different from modern financial markets and business decisions — and the biases it brings are systematic. Named and understood, they can be accommodated. Unnamed, they produce predictable and costly errors.