The method is finding widespread use in the UK innovation sector, is offered by numerous facilitation companies and has been trialled within the UK civil service.
Michael Hewitt-Gleeson claims that the method was initially developed during a brainstorming session he had with Edward de Bono and Eric Bienstock in 1983.
The premise of the method is that the human brain thinks in a number of distinct ways which can be identified, deliberately accessed and hence planned for use in a structured way allowing one to develop strategies for thinking about particular issues. Dr de Bono identifies five distinct states in which the brain can be "sensitised". In each of these states the brain will identify and bring into conscious thought certain aspects of issues being considered (e.g. gut instinct, pessimistic judgement, neutral facts).
Perhaps the most compelling example presented is the idea of sensitivity to "mismatch" stimuli as a particularly strong tendency. This is presented as being a valuable survival instinct - because in the natural world the thing that is out of the ordinary may well be dangerous. This is identified as the root of negative judgement and critical thinking.
Six distinct states are identified
Neutrality (white) - considering purely what information is available, what are the facts?
Feeling (Red) - instinctive gut reaction or statements of emotional feeling (but not any justification)
Negative judgement (Black) - logic applied to identifying flaws or barriers, seeking mismatch
Positive Judgement (Yellow) - logic applied to identifying benefits, seeking harmony
Creative thinking (Green) - statements of provocation and investigation, seeing where a thought goes
Process control (Blue) - thinking about thinking
In order to make it easier to clearly identify and work with these states the use of coloured hats as metaphors for them is used; each state is symbolised by the act of putting on a colored hat, either actually or imaginatively. The use of these metaphors also allows more complete and elaborate definition of the states thus getting past the preconceptions inherent in using peoples current language.
Furthermore Dr de Bono asserts that these states are associated with distinct chemical states of the brain - although no details or evidence of this are presented.