From our first member exclusive: An excerpt from New York Times writer Charles Duhigg’s bestselling book, The Power of Habit, which examines the science behind how we form and change our habits, and how companies are profiting off of them (sign up here to join):

“‘Some doctors were fine, and some were monsters,’ one nurse who worked at Rhode Island Hospital in the mid-2000s told me. ‘We called it the glass factory, because it felt like everything could crash down at any minute.’

“To deal with these tensions, the staff had developed informal rules — habits unique to the institution — that helped avert the most obvious conflicts. Nurses, for instance, always double-checked the orders of error-prone physicians and quietly made sure that correct doses were entered; they took extra time to write clearly on patients’ charts, lest a hasty surgeon make the wrong cut. One nurse told me they developed a system of color codes to warn one another.

“‘We put doctors’ names in different colors on the whiteboards,’ she said. ‘Blue meant ‘nice,’ red meant ‘jerk,’ and black meant, ‘whatever you do, don’t contradict them or they’ll take your head off.”‘”