Oaksford and Chater recast the Wason selection task as optimal data selection, turning a classic 'human error' into rational choice

The Wason selection task — in which participants choose which cards to turn over to test a conditional rule — had long been read as psychology's cleanest demonstration that humans reason badly: most people fail to select the cards that formal logic (the material conditional) says would falsify the rule. Oaksford and Chater's probabilistic reanalysis inverts the verdict. In their précis they report that "Data from conditional reasoning, Wason's selection task, and syllogistic inference are captured by recasting these problems probabilistically," and that "the probabilistic approach makes a variety of novel predictions which have been experimentally confirmed."

The mechanism is optimal data selection: rather than treating card choice as an attempt at logical falsification, the model treats it as a decision about which observations would be most informative — the cards people actually pick are those that maximize expected information gain (Shannon-entropy reduction) about which hypothesis is true, given plausible prior probabilities about how rare the named properties are. Under that objective, the "wrong" answers become the choices a well-calibrated Bayesian agent should make. The specific expected-information-gain mathematics comes from Oaksford and Chater's earlier "optimal data selection" analysis (1994), not opened in this note.

This is the concrete demonstration of the broader reframing that claim-oaksford-chater-redefine-rationality-as-reasoning-about-uncertainty states in general: rationality measured as calibrated inference under uncertainty rather than as conformity to logic. It sits alongside other "the yardstick was wrong, not the reasoner" arguments in the vault — Gigerenzer's ecological rationality and Simon's bounded rationality (rationality-continuity-problem, claim-simon-satisficing-and-heuristic-search-same-move) — whose mutual compatibility with rational analysis is still open (question-verify-ecological-rationality-vs-rational-analysis-compatibility).

This "rational analysis" move — explaining behaviour as the optimal solution to the problem the environment poses (Anderson 1990) — is, from a different lineage, the same bet Werbos made when he framed optimization as a theory of mind (claim-werbos-1997-optimization-consciousness-chapter, and its origin in claim-werbos-backprop-from-freud-own-account). The bridge and its limits are worked out in claim-optimization-as-theory-of-mind-two-lineages (promoted from the 2026-07-11 hop capture).