In 1985, psychologist and author Edward de Bono published a book titled Six Thinking Hats.
The book presents a method that groups of people working together can use to leverage parallel thinking skills and limit disputes.
[citation needed] Construction workers are required to wear hard hats when on a job site.
The head covering color was supposed to be yellow but many of the Jewish people coming into the city chose to wear red instead, with the exception of those of Levantine origin.
While there is no solid proof for the reasoning of this change, many believe it is because of the stigma surrounding the color yellow which was also used to mark pimps and prostitutes.