Unprogrammed movement follows from two things: first from the way in which the various occupation spaces are disposed in the spatial complex, coupled to the degree to which each actor as an origin and a destination for movement between occupation spaces; second, from how this disposition relates to the spatial configuration of the complex itself.
Hillier, B. (1996, 2007), Space is the Machine: A Configurational Theory of Architecture. Space Syntax: London, UK. pp.255