Critical move

A critical move occurs when the gap between the best decision and reasonable alternatives is large enough to change something important: a win may become a draw, equality may become a disadvantage, or an easy defense may become very difficult.

It does not have to be spectacular. It may be a piece trade, a decision about pawn structure, meaning the arrangement of the pawns, or a commitment that cannot later be undone. What matters is the narrow margin for error and the need for extra time and verification. De Groot’s four-stage model helps explain why a player first orients to the position, then explores options, and finally verifies the choice.

A critical move is not necessarily a forced move. Several legal and attractive choices may exist, while only one or a few preserve the desired outcome. Double-edged positions often contain critical decisions because both sides have immediate opportunities and risks.