Compatibility principle
Also known as: Stimulus–response compatibility
An attribute counts more when it matches the form of the response.
What it means
The principle that an attribute of the options receives more weight in a judgment when it is compatible with — expressed in the same units or scale as — the required response. When the answer must be a dollar amount, monetary attributes loom larger; when the answer is a choice, qualitative or comparative attributes dominate, because compatible information is easier to map onto the output and so is processed more fluently. The principle is a central explanation for preference reversals: pricing a gamble makes its payoff (also in dollars) decisive, while choosing weights the probability of winning, flipping the apparent preference. It generalizes a classic idea from perception and action — that responses are faster and more accurate when stimulus and response correspond — into the realm of judgment and value. It matters because it shows that the response format itself, not just the options, shapes which attributes drive a decision.
The roots in perception and action
The idea starts far from value. Fitts and Seeger (1953) had people respond to lights with button presses and found them faster and more accurate when the spatial layout of the lights matched the layout of the buttons; a mismatch forced a mental translation step that cost time and bred errors. The compatibility principle carries this into judgment. An attribute stated in the same units as the required answer needs no translation, so it flows more easily into the response and picks up weight along the way. What began as a fact about hands and lights became a claim about which features of an option the mind lets count, and why the wording of the question quietly edits the answer.
What the process evidence shows
The signature prediction is that identical options yield different weights under different response formats, and process tracing bears it out. Preference reversals between pricing and choosing gambles, first reported by Lichtenstein and Slovic (1971), have replicated for five decades. Eye-tracking sharpens the mechanism: Alos-Ferrer, Jaudas and Ritschel (2021) found that a monetary pricing frame shifts fixations toward payoffs while a choice frame pulls the eye to probabilities, and the overpricing of high-payoff bets tracks that attentional shift. Slovic, Griffin and Tversky (1990) showed the same logic outside money, where a grading response overweighted past grades relative to class rank. The effect is not a curiosity of gambles but a general feature of how response scales recruit attention.
Where it shows up
Any task that fixes the units of the answer risks tilting the weights. Contingent-valuation surveys that ask willingness-to-pay in dollars pull attention toward monetary features and away from harder-to-price ones. Health economists find that valuing the same health state with a standard gamble versus a time trade-off gives systematically different numbers, partly because each response scale is compatible with a different facet of the outcome. Salary talks, procurement scorecards, and job-offer comparisons behave the same way: whether the decision is posed as a number to match or an option to pick changes which attributes end up deciding it. The lesson for design is to choose the response format deliberately, because it is never neutral about what matters.
Related but distinct: the prominence effect
Compatibility is easy to confuse with the prominence effect, which Tversky, Sattath and Slovic isolated in the same 1988 paper. Prominence says the more important attribute dominates choice more than matching; compatibility says the attribute sharing the response's units gains weight regardless of its importance. The two often push in the same direction. In the classic gamble, the probability of winning is both the prominent attribute and the choice-compatible one, so choice and compatibility predictions coincide. But they are separable, and designs that vary the units of the response while holding importance fixed still find a compatibility effect on its own. Treat them as two distinct levers on the same reversal, not one restated twice.
Examples
Asked what they would pay for a used car, buyers dwell on the repair bills it might carry; asked which of two cars they would rather own, they go by looks and feel.
Asked to name a salary they would accept, candidates weigh the money-shaped features — bonus, pension; asked to pick between two offers, the shorter commute and the nicer team suddenly dominate.
Asked how many months of healthy life they would trade for a cure, patients dwell on the time; asked to accept a gamble on an operation, they weigh the odds of survival.
A survey asking what a wetland is worth in dollars pulls answers toward fees and cleanup costs; asking whether to preserve it foregrounds the birds no price tag captures.
First described in Tversky, Sattath & Slovic (1988); Slovic, Griffin & Tversky (1990).
Key references
- Alos-Ferrer, C., Jaudas, A., & Ritschel, A. (2021). Attentional shifts and preference reversals: An eye-tracking study. Judgment and Decision Making, 16(1), 57-93. doi.org/10.1017/S1930297500008305
- Slovic, P., Griffin, D., & Tversky, A. (1990). Compatibility effects in judgment and choice. In R. Hogarth (Ed.), Insights in decision making: A tribute to Hillel J. Einhorn (pp. 5-27). University of Chicago Press. scholarsbank.uoregon.edu/server/api/core/bitstreams/73f58c4b-4f2e-4423-9232-2c22a7787a7a/content
- Tversky, A., Sattath, S., & Slovic, P. (1988). Contingent weighting in judgment and choice. Psychological Review, 95(3), 371-384. doi.org/10.1037/0033-295X.95.3.371
- Lichtenstein, S., & Slovic, P. (1971). Reversals of preference between bids and choices in gambling decisions. Journal of Experimental Psychology, 89(1), 46-55. doi.org/10.1037/h0031207
- Fitts, P. M., & Seeger, C. M. (1953). S-R compatibility: Spatial characteristics of stimulus and response codes. Journal of Experimental Psychology, 46(3), 199-210. doi.org/10.1037/h0062827