In his textbook on environmental psychology, Robert Gifford outlines six goals that social designers aim to achieve during a project. The first is to match the needs of occupants to a physical setting. This is known as habitability, congruence, or goodness of fit and is the overarching goal of the social design philosophy. The second goal is to satisfy building users. This is important because occupants spend much of their time in the finished space. Third, social design aims to change behavior. Depending on the context of the project, this may mean increasing productivity in office staff, encouraging pro-social behavior in an assisted-living facility, or decreasing aggression in prison inmates. Fourth, enhancement of personal control within a space is key. When an occupant can alter a setting to suit his or her needs, greater satisfaction and stress reduction is generally experienced. The fifth goal is to facilitate social support among occupants. Enhancing cooperation among those who live or work in a space is often desirable. Lastly, the sixth goal is to employ imageability. This occurs when a building helps occupants and visitors navigate the building efficiently and successfully.