Peter J. Marshall is Assistant Professor of Psychology at Temple University. His research interests include temperament, attachment, and the utility of electrophysical measures of nervous system functioning in research on social, emotional, and cognitive development in infancy and early childhood.LNathan A. Fox is Professor of Human Development at the University of Maryland, College Park. His interests mainly concern the biological bases of individual differences in infant temperament and the role of early experience as it affects brain and behavior in the realm of social and emotional c...