1 King's Centre for Military Health Research, Institute of Psychology, Psychiatry and Neuroscience, King's College London, London SE5 9RJ, UK; Department of Experimental Psychology, University of Oxford, Oxford, UK. Electronic address: victoria.williamson@kcl.ac.uk.
2 King's Centre for Military Health Research, Institute of Psychology, Psychiatry and Neuroscience, King's College London, London SE5 9RJ, UK; Combat Stress Research Department, Combat Stress, Surrey, UK.
3 Phoenix Australia Centre for Posttraumatic Mental Health, Department of Psychiatry, University of Melbourne, Carlton, VIC, Australia.
4 King's Centre for Military Health Research, Institute of Psychology, Psychiatry and Neuroscience, King's College London, London SE5 9RJ, UK.