Köhler was also vocal in his stance against behaviorism, another competing school of thought in North America. At the time, behaviourism focused solely on overt acts that were easily observable and measurable. Inner thoughts, feelings, and processes that occurred between the presentation of a stimulus and the onset of behaviour were considered part of a black box not easily understood. This black box, which could be described as cognition today, was not accessible and therefore should be discarded from psychology as being something unimportant. Köhler criticized the behaviourists' dismissal of direct experience. They said that it was not measurable, and therefore did not contribute to the furthering of human understanding.