This thesis comprises three studies of the meaning of adults’ unresolved states of mind with respect to attachment (U/d) in the Adult Attachment Interview.

The first study is a historical analysis of the conceptualisation of “trauma” in the unresolved state of mind classification, drawing on published and unpublished texts by Mary Main and colleagues. The paper traces the emergence of the construct of an unresolved state of mind, and places this in the context of wider contemporary discourses of trauma, in particular posttraumatic stress disorder and discourses about child abuse.

In the second study, individual participant data were used from 1,009 parent-child dyads across 13 studies. Interviewees with or without unresolved loss/abuse were differentiated by subsets of commonly occurring indicators of unresolved loss/abuse. Predictive models suggested a psychometric model of unresolved states of mind consisting of a combination of these common indicators, which was weakly predictive of infant disorganised attachment. There was no significant association between unresolved “other trauma” and infant disorganised attachment. The findings provide directions for further articulation and optimisation of the unresolved state of mind construct.

In the third study, first-time pregnant women (N = 235) participated in the Adult Attachment Interview while indicators of autonomic nervous system reactivity were recorded. Unresolved speech about loss was associated with increased heart rate. Participants classified as unresolved showed a decrease in pre-ejection period and blunted skin conductance level throughout the interview. Unresolved states of mind may be associated with physiological dysregulation, but questions remain about the psychological mechanisms involved.

This thesis contributes towards further clarification of the unresolved state of mind construct by examining its historical context, psychometric characteristics, and psychophysiological mechanisms. Further exploratory and theoretical work should focus on improving the definition and validity of the unresolved state of mind construct, to gain a better understanding of how attachment-related experiences of loss and trauma are processed and how this might affect parenting behaviour.