1. Department of Psychology, Gilmer Hall Room 102, University of Virginia, Charlottesville, VA 22903, USA
2. Department of Psychology, 3137 Sennott Square, 210 S. Bouquet Street, Pittsburgh, PA 15260, USA
3. Robotics Institute, Carnegie Mellon University, 5000 Fifth Avenue, Pittsburgh, PA 15213, USA
4. School of Computing Sciences, University of East Anglia, Earlham Road, Norwich NR4 7TJ, UK
5. Disney Research, Pittsburgh, 4615 Forbes Avenue, Pittsburgh, PA 15213, USA