Physiological Reactivity to Infant Crying and Observed Maternal Sensitivity Katharina J. Joosen Centre for Child and Family Studies, Leiden University Judi Mesman Centre for Child and Family Studies, Leiden University Marian J. Bakermans-Kranenburg Centre for Child and Family Studies, Leiden University Leiden Institute for Brain & Cognition Suzanne Pieper Centre for Child and Family Studies, Leiden University Philip S. Zeskind Department of Pediatrics, Levine Children’s Hospital at Carolinas Medical Center Marinus H. van IJzendoorn Centre for Child and Family Studies, Leiden University Leiden Institute for Brain & Cognition Relations between maternal sensitivity and physiological reactivity to infant crying were examined using measures of heart rate (HR) and respiratory sinus arrhythmia (RSA) in 49 mothers of second-born infants. Using the Ainsworth Sensitivity Scale, an independent assessment of maternal sensitiv- Correspondence should be sent to Judi Mesman, Centre for Child and Family Studies, Leiden University, PO Box 9555, 2300 RB Leiden, the Netherlands. E-mail: mesmanj@fsw. leidenuniv.nl Infancy, 1–18, 2012 Copyright Ó International Society on Infant Studies (ISIS) ISSN: 1525-0008 print / 1532-7078 online DOI: 10.1111/j.1532-7078.2012.00122.x