In this view, the mind is no more than an opaque black box inserted between stimulus and response. As no one can see inside of it, it is not worthy of study. This extreme antimentalism of the behaviorists has been frequently criticized and was finally put to rest by the cognitive revolution in the 1960s. While the behaviorists made invaluable contributions to psychology regarding the fundamental principles of behavioral change, their devaluing and dismissal of subjective experience was extremely limiting.