One of Freud’s major assumptions was that unconscious or repressed forces influence our conscious thoughts and behaviors. An esteemed scientist says 80–90% of what we do is unconscious (Kandel, 2008). For instance, when you speak, you use correct grammar while paying little or no conscious attention to doing so. Patterns of brain activity can actually reveal which a person is going to make before he or she is aware of it. In one study, researchers took brain scans of people while they held a button in each hand and were instructed to push either button. The brain scans revealed which hand people were going to use before the people were even aware they had made a decision (Haynes, 2008). In contrast to Freud’s theory of the repressed unconscious forces, cognitive neuroscientists developed a different concept, called implicit or nondeclarative memory (p. 246) (Solms, 2006).