Negative attractor is the thing or location where the natural movement rates decrease, though this may of course be compensated by the numbers of people attracted to it for other reasons. A large train station is one example of this phenomenon.
Hillier, B., Penn, A., Hanson, J., Grajewski, T., and Xu, J. (1993), Natural Movement: or. Configuration and Attraction in Urban Pedestrian Movement. Environment Planning B, 20(1) 29-66. pp. 42-44; Hillier, B. (1996, 2007), Space is the Machine: A Configurational Theory of Architecture. Space Syntax: London, UK. pp.189