[1] Umea Univ, Dept Psychol, S-90187 Umea, Sweden
[2] Linkoping Univ, Dept Behav Sci & Learning, Linkoping, Sweden
[3] San Diego State Univ, San Diego, CA 92182 USA
[4] Boston Univ, Dept Psychol, Boston, MA 02215 USA
[5] Karolinska Inst, Psychiat Sect, Dept Clin Neurosci, Stockholm, Sweden