Mentalization is the ability to evoke, understand, and reflect upon one's own and others' state of mind.
Mentalizing denotes the capacity to imagine and think explicitly about mental states, namely thoughts, feelings, intentions, beliefs, motives, emotions, desires and needs.
Reflective Function (RF) is the ability to imagine mental states in the self and in others.
Through this capacity for reflection, individuals develop the ability to understand their own behavioural responses and the responses of others as a meaningful attempt to communicate inner mental states.
RF is the uniquely human capacity to make sense of each other.
References
Allen, J.G., Fonagy, P., & Bateman, A.W. (2008). Mentalizing in Clinical Practice. Washington, DC: American Psychiatric Publishing, Inc.
Fonagy, P., Gergely, G., Jurist, E., & Target, M. (2002). Affect Regulation, Mentalization and the Development of the Self. New York: Other Press.
Fonagy P, Target M (1997) Attachment and reflective function: Their role in self-organization. Development & Psychopathology 9:679-700.
Fonagy, P., Steele, M., Steele, H., & Target, M. (1997). The Reflective-functioning manual, Version 4.1 for application to Adult Attachment Interviews. Unpublished Manuscript. University of London.
Fonagy P, Steele M, Steele H., & Target M. (1998) Reflective Function Manual (Version 5) for Application to Adult Attachment Interviews. . University College London, London, UK.