Some difficulties in interpreting psychophysiological research with children.

Mona El-Sheikh and her colleagues have assembled an impressive series of studies for this monograph. To date, researchers interested in the consequences of marital conflict on children have focused primarily on the main effects of psychological variables. Although these studies have been invaluable in helping us to better understand risk and resiliency factors associated with children’s exposure to marital conflict, future research will almost certainly be conducted at multiple levels of analysis, spanning genes to behavior (Ciccetti, 2008). The authors’ work examining the conjoint effects of marital conflict and biological vulnerability on children’s externalizing behaviors is therefore a welcome addition to the literature and likely marks a transition to a new generation of research. Among the few authors who have examined biological moderators of outcomes among children exposed to marital conflict, respiratory sinus arrhythmia (RSA), an index of parasympathetic nervous system (PNS) functioning, has been the predominant measure used (e.g., El-Sheikh & Whitson, 2006; Katz & Gottman, 1995). In this monograph, El-Sheikh and colleagues extend this work in a number of important ways. First, they include a measure of sympathetic nervous system (SNS) functioning and examine interactions between the SNS and PNS in predicting children’s externalizing behaviors. Second, they provide detailed descriptions of and comparisons among several alternative models of autonomic nervous system (ANS)–behavior relations, grounding their hypotheses firmly in theory. Finally, they conduct the same protocol with three separate samples of children (total N5 577), recognizing that three-way interactions, which are required to test their hypotheses, are often spurious and difficult to replicate. The authors should be applauded for this painstaking research effort. Although their pattern of results is complex, the findings indicate that children’s physiological functioning is clearly related to their externalizing behaviors in the context of marital conflict.