1. School of Psychology, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
2. Center for Logic, Language, and Cognition, Department of Computer Science, University of Torino, C.so Svizzera 185, 10149 Torino, Italy
3. Department of Psychology, University of Oslo, PO Box 1094, Blindern, 0317 Oslo, Norway
4. Department of Experimental Psychology, University of Oxford, South Parks Road, Oxford OX1 3UD, UK