have a "reference point", which are better known than others, more frequently visited and more visible. There are other kinds of distortions as well. Furthermore, there the distortion in distance estimation and the distortion in angle alignment. Distortion in angle alignment means that your personal north will be viewed as "the north". The map is mentally represented according to the orientation of the personal point of view of learning. Since perceived distortion is "subjective" and not necessarily correlated with "objective distance", distortions can happen in this phenomenon too. There can be an overestimation in downtown routes, routes with turns, curved routes and borders or obstacles. Spatial knowledge A classical approach to the acquisition of spatial knowledge, proposed by Siegel & White in 1975, defines three types of spatial knowledge – landmarks, route knowledge and survey knowledge – and draws a picture of these three as stepstones in a successive development of spatial knowledge. Within this framework, landmarks can be understood as salient objects in the environment of an actor, which are memorized without information about any metric relations at first. By traveling between landmarks, route knowledge evolves, which can be seen as sequential information about the space which connects landmarks. Finally, increased familiarity with an environment allows the development of so-called survey knowledge, which integrates both landmarks and routes and relates it to a fixed coordinate system, i.e. in terms of metric relations and alignment to absolute categories like compass bearings etc. This results in abilities like taking shortcuts never taken before, for example. More recently, newer findings challenged this stairway-like model of acquisition of spatial knowledge. Whereas familiarity with an environment seems to be a crucial predictor of navigational performance indeed, in many cases even survey knowledge can be established after minimal exploration of a new environment. In this context, Daniel R. Montello proposed a new framework, indicating, that the changes in spatial knowledge ongoing with growing experience are rather quantitative than qualitative, i. e. different types of spatial knowledge become just more precise and confident. Furthermore, the use of these different types seems to be predominantly task-dependent, which leads to the conclusion that spatial navigation in everyday life requires multiple strategies with different emphasis on landmarks, routes and overall survey knowledge. Space classification The space can be classified according to its extension as proposed by Montello, distinguishing between figural space, vista space, environmental space and geographical space. Figural