1. Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08544
2. Brain Institute, Federal University of Rio Grande do Norte, Natal 59076-550, Brazil
3. Center for Advanced Study of Collective Behavior, University of Konstanz, Konstanz 78464, Germany
4. Department of Collective Behavior, Max Planck Institute of Animal Behavior, Konstanz 78464, Germany
5. Department of Psychology, Princeton University, Princeton, NJ 08544