An alternative scoring method for skin conductance responding in a differential fear conditioning paradigm with a long-duration conditioned stimulus


  • Suzanne L. Pineles,

    1. National Center for PTSD, Women's Health Sciences Division, VA Boston Healthcare System, Boston, Massachusetts, USA
    2. Department of Psychiatry, Boston University School of Medicine, Boston, Massachusetts, USA
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  • Matthew R. Orr,

    1. Department of Physics, University of Alabama in Huntsville, Huntsville, Alabama, USA
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  • Scott P. Orr

    1. Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, USA
    2. Department of Veterans Affairs Medical Center, Manchester, New Hampshire, USA
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  • This research was supported by U.S. Public Health Service grant R01-MH60315 and Department of Veterans Affairs Merit Review grant to Scott P. Orr. Additional support was provided to Suzanne Pineles by the Department of Veterans Affairs, Clinical Sciences R&D Service, Career Development Award Program. We thank Heike Croteau, Michael Macklin, Sgt. Thomas Flemming, Sheeva Mostoufi, and Erin Rowe for their assistance with this project. We would also like to express our appreciation to the police and firefighters for their willingness to participate.

Address reprint requests to: Scott P. Orr, VA Medical Center, Research Service (151), 718 Smyth Road, Manchester, NH 03104. E-mail:


Researchers examining skin conductance (SC) as a measure of aversive conditioning commonly separate the SC response into two components when the CS-UCS interval is sufficiently long. This convention drew from early theorists who described these components, the first- and second-interval responses, as measuring orienting and conditional responses, respectively. The present report critically examines this scoring method through a literature review and a secondary data analysis of a large-scale study of police and firefighter trainees that used a differential aversive conditioning procedure (n=287). The task included habituation, acquisition, and extinction phases, with colored circles as the CSs and shocks as the UCS. Results do not support the convention of separating the SC response into first- and second-interval responses. It is recommended that SC response scores be derived from data obtained across the entire CS-UCS interval.