Environmental knowledge is that which is acquired about the real world environment through any number of processes. Direct interaction would be the most obvious, but knowledge of the environment can be attained in many other ways. Media, in the form of written descriptions, pictures, drawings or other schematic representations, as well as verbal descriptions passed on by other individuals can also provide an adequate representation of the environment for purposes of spatial knowledge acquisition. Environmental knowledge has commonly been subdivided into three levels. This concept, refined by Hart and Moore [51] from an interpretation of earlier work by Piaget and Inhelder [80], include: landmark knowledge, route knowledge and survey knowledge. These have been thought of and studied as a developmental sequence following from landmark, to route and culminating in survey knowledge. Recently there have been some changes suggested to this dominant framework of environmental knowledge, specifically dealing with the sequential nature of the three forms of knowledge [73]. There is some argument that in the earliest stages of spatial knowledge acquisition by adults, higher level knowledge is being acquired and coded at the same time as the most primitive spatial information.
Hart and Moore summarized the developmental process through which individuals pass during their acquisition of environmental knowledge initially [51]. As was stated above the developmental process includes landmark, route and survey level knowledge. The learner will develop a fully metric internal representation of space, through stages of egocentric to allocentric knowledge and from simple topological spatial understanding.