1. Systems Neurobiology Laboratories, Salk Institute for Biological Studies, La Jolla, CA, USA.
2. Center for Spatial Perception and Concrete Experience, University of Southern California, Los Angeles, CA, USA.
3. Herbert Wertheim School of Optometry & Vision Science, University of California Berkeley, Berkeley, CA, USA.
4. Department of Physics, Loughborough University, Loughborough, UK.