The Dynamic Identity Fusion Index: A New Continuous Measure of Identity Fusion for Web-Based Questionnaires Juan Jime ´nez 1 ,A ´ ngel Go ´ mez 1 , Michael D. Buhrmester 2,3 , Alexandra Va ´zquez 1 , Harvey Whitehouse 4 , and William B. Swann 5 Abstract We introduce a computer-based measure of ‘‘identity fusion,’’ a form of group alignment char- acterized by a visceral feeling of oneness with a group. Past measures of identity fusion (a single pictorial item and a 7-item verbal scale) have demonstrated a unique capacity to predict will- ingness to engage in extreme pro-group behaviors (e.g., fighting and dying for one’s group). The Dynamic Identity Fusion Index (DIFI) combines the simplicity of the single pictorial item with the higher fidelity afforded by a continuous scale. The DIFI runs on a script written in JavaScript and works on both traditional computers and modern touch-pad devices. It allows for simul- taneous assessment of self-group distance and overlap, two conceptually distinct components of group alignment. Study 1 assessed the criterion validity of the two components of the DIFI and discovered that the overlap metric was a better indicator of identity fusion than the dis- tance metric. Four more studies demonstrated DIFI’s temporal stability (Study 2), convergent and discriminant validity (Study 3), and predictive validity, specifically endorsement of pro-group behaviors (Study 4). We discuss implications of the DIFI for future research on identity fusion and recommend when it should be used. Keywords identity fusion, visual analog scale, computer-based measure 1 Faculty of Psychology, Department of Social and Organizational Psychology, Universidad Nacional de Educacio ´ n a Distancia (UNED), Madrid, Spain 2 School of Anthropology, University of Oxford, Oxford, UK 3 Queen’s University, Belfast, UK 4 University of Oxford, Oxford, UK 5 Department of Psychology, University of Texas at Austin, Austin, TX, USA Corresponding Author: Juan Jime ´nez, Faculty of Psychology, Department of Social and Organizational Psychology, Universidad Nacional de Educacio ´n a Distancia (UNED), Madrid 28040, Spain. Email: juanjimenez@psi.uned.es Social Science Computer Review 1-14 ª The Author(s) 2015 Reprints and permission: sagepub.com/journalsPermissions.nav DOI: 10.1177/0894439314566178 ssc.sagepub.com by guest on January 20, 2015 ssc.sagepub.com Downloaded from