作者单位:Department of Psychology, 3137 Sennott Square, 210 S. Bouquet Street, Pittsburgh, PA 15260, USA[1]Department of Psychology, Gilmer Hall Room 102, University of Virginia, Charlottesville, VA 22903, USA[2]Robotics Institute, Carnegie Mellon University, 5000 Fifth Avenue, Pittsburgh, PA 15213, USA[3]School of Computing Sciences, University of East Anglia, Earlham Road, Norwich NR4 777 UK[4]