Obviously, by definition, unconscious processes are less available than conscious processes. Yet there is traffic between the two. For example, there is a well-known tendency for all training to move from halting, difficult conscious steps to smooth, semi-automatic performance. That, as Anderson recognised, is a shift from conscious to unconscious control as mastery is achieved. Anderson's key distinction is between 'declarative knowledge' (knowledge we are aware of and can talk about) and 'procedural knowledge', which guides action and decision-making, but which happens outside of conscious 'view'.