The `thinking hat/cap' goes back much further than that. In some of the Betty Boop cartoons (1930s ??), there is a professor who, in order to come up with a solution to a problem, always starts with `Let me put my thinking hat on'. G.Heinlein > > I believe that Gyro's thinking cap was created by writer Vic Lockman. It > debuted sometime in the late 1960s.