1. Department of Psychology, University of Durham, South Road, Durham DH1 2NR, UK
2. Developmental Ethology and Cognitive Psychology Group, Center for Smell, Taste, and Food Science, CNRS (UMR 6265), Université de Bourgogne, 21078 Dijon Cedex, France
3. The James Cook University Hospital, Middlesbrough TS4 3BW, UK