1. Department of Psychology, University of CaliforniaSanta Barbara, CA 93106-9660, USA
2. Department of Anthropology, University of CaliforniaSanta Barbara, CA 93106-9660, USA
3. Department of Psychology, University of TexasAustin, TX 78712, USA
4. Department of Comparative Human Development, The University of ChicagoChicago, IL 60637, USA