Psychopathic murderers are often portrayed as cold-blooded, emotionless and lacking in remorse¹, but they are also adept at lying and at feigning the emotions in which they are deficient. Here we adapt a test known as the Implicit Association Test (IAT)², which was previously used to assess concealed prejudices, to show that psychopathic murderers have abnormal cognitive associations regarding violence, which may underpin their actions. Such implicit measures may provide us with an important insight into the criminal mind.

1. School of Psychology, Cardiff University, Cardiff CF10 3YG, UK
2. South Wales Forensic Psychiatric Service, Caswell Clinic, Glanrhyd Hospital, Mid Glamorgan CF36 4LN, UK
3. Department of Psychological Medicine, University of Wales College of Medicine, Heath Park, Cardiff CF14 4XN, UK
4. HM Prisons, Grendon and Springhill, Grendon Underwood, Aylesbury, Buckinghamshire HP18 OTL, UK

Correspondence to: Nicola S. Gray^1,2 e-mail: Email: grayns@cardiff.ac.uk