Green hat: generate new ideas and creative possibilities

The green hat is for generating alternatives and possibilities without evaluation — quantity and novelty over quality and correctness.

Why it works

Evaluation and generation are cognitively incompatible when concurrent: the evaluative stance suppresses ideas that seem risky, unlikely, or incomplete before they can be articulated. By explicitly separating the generative phase (green hat) from the evaluative one (black and yellow hats), the method reduces this suppression — the same logic as classic brainstorming’s "defer judgment" rule, which has partial experimental support.

How to do it

1. Signal the green-hat phase explicitly: "We are generating only — no evaluation right now."
2. Use lateral thinking techniques (random entry, provocation) within the green hat if the group gets stuck.
3. Go for quantity: aim for at least ten ideas before considering any of them.
4. Note every idea, including absurd or impractical ones — they may become stepping stones.

Evidence

Separating idea generation from evaluation increases the number and diversity of ideas considered; classic brainstorming research is mixed on whether group brainstorming beats individual brainstorming, but the separation of generation from evaluation phases is consistently supported. (observational)

Classic brainstorming group-versus-individual comparisons consistently favor individual brainstorming (nominal groups) over interactive groups; the green hat benefits from the generative-versus-evaluative separation, not necessarily from group interaction per se.

Sources

• Osborn (1953), Applied Imagination (original brainstorming formulation)

Common mistake

Evaluating ideas as they arise ("that won’t work because…") which collapses the green hat back into ordinary discussion and defeats the generative phase.