1. Department of Biological Sciences and Department of Animal Sciences, Purdue University, 915 West State Street, West Lafayette IN 47907, USA
2. Animal Behavior Graduate Group and Department of Evolution and Ecology, University of California, Davis, CA 95616, USA
3. Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
4. Department of Psychology, University of Pennsylvania, Philadelphia, PA 19104, USA
5. Marketing Department, the Wharton School, University of Pennsylvania, Philadelphia, PA 19104, USA
6. School of Biological Sciences, University of Sussex, Brighton, BN1 9QG, United Kingdom