The main restriction on Thinking and tool is a powerful technique used to look at decisions from different points of view. the hats allow us to think and say things that we could not otherwise think and say without risking our egos.
The six hats give us a means for directing attention to six different aspect of the matter. Each of the six thinking hats has a color: white, red, black, yellow ,green,blue. The color provides the name for hat. Color is important.How else could you distinguish between the hats ? Different shapes would again be difficult to learn and would be confusing. Color makes the imaging easier.