1. Visual Performance Laboratory, University of California–San Diego, La Jolla
2. Swartz Center for Computational Neuroscience, University of California–San Diego, La Jolla
3. Department of Computer Science, National Chiao Tung University, Hsinchu, Taiwan
4. Swartz Center for Computational Neuroscience, University of California–San Diego, La Jolla3Department of Computer Science, National Chiao Tung University, Hsinchu, Taiwan