1. Department of Psychology, School of Social Sciences, Reykjavik University, 102 Reykjavik, Iceland
2. Centre of Public Health Sciences, Faculty of Medicine, University of Iceland, 101 Reykjavik, Iceland
3. Department of Psychiatry, McLean Hospital, Harvard Medical School, Boston, MA 02115, USA
4. Department of Psychology and Neuroscience, Temple University, Philadelphia, PA 19122, USA
5. Child Study Center, Department of Psychology, Virginia Tech, Blacksburg, VA 24060, USA