1 Department of Bio and Brain Engineering, College of Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea.
2 Program of Brain and Cognitive Engineering, College of Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea.
3 Center for Neuroscience, University of California, Davis, Davis, CA, United States.
4 Department of Psychology, University of California, Davis, Davis, CA, United States.
5 Department of Psychology, University of Pittsburgh, Pittsburgh, PA, United States.
6 Learning Research and Development Center, University of Pittsburgh, Pittsburgh, PA, United States.