De Groot's four-stage model

De Groot's four-stage model summarizes a pattern of thought observed by psychologist and chess master Adriaan de Groot through think-aloud protocols. In those studies, players examined a position and verbalized their thoughts while searching for a move. The model is meant to describe the organization of a complex decision, not impose a rigid recipe.

The four stages

1. Orientation: grasp the main features of the position and form an initial impression of problems, opportunities, and goals.
2. Exploration: generate candidate moves, meaning options worth analyzing, and examine some possible continuations.
3. Investigation: study the most promising option more deeply and compare it with relevant alternatives.
4. Proof: review the final choice, verify variations, and look for a flaw before playing the move.

The stages can repeat, overlap, or become very brief. A player may return from investigation to exploration after finding an unexpected defense. Accumulated knowledge and chunking influence the process from the start because they help familiar configurations stand out and reduce the number of plausible options.

Later expertise research has qualified the idea that strength comes simply from searching many more moves. Strong players often direct search better and identify relevant possibilities earlier. The model remains useful for separating an initial impression from the verification needed on a critical move, a decision with little margin for error, and for understanding how the Einstellung effect can narrow exploration too soon.