The pesticide Zyklon B contained a chemical which gave it a nutty smell so as to alert people to its presence when it was used on farms. When the pesticide was used in gas chambers the chemical was removed so that it would take longer for those in the chambers to detect it, thus reducing the time in which they had to panic. Of course, this 'humanitarian' act did not help in any meaningful way but knowledge (the ability to detect the pesticide) is only useful when it can be acted on, if it cannot then it merely prolongs pain. Learned helplessness is common but the cage floors don't have the same amount of electricity running through them.