This study provides an empirical demonstration of dissociable contributions of neurological and psychological factors to awareness of deficits in TBI. Trait proclivity to mobilize defence mechanisms in response to anxiety-provoking situations can be measured, and strongly predicts impaired awareness. Importantly, measures of psychological reactions were independent of responses to the neurological deficits themselves, discriminating between psychological and neurological contributions to impaired awareness. The importance of identifying psychological reactions to impaired awareness and hindering rehabilitation success is highlighted, and vital for clinicians to consider during the rehabilitation process. Psychological reactions to TBI can be identified using well-validated, quantitative measures of the use of psychological defences (e.g., Cramer's Thematic Apperception Test scoring system), and the authors suggest this is a critical step to properly characterize and manage awareness in patients during treatment. Although only TBI patients were examined, the results may inform impaired awareness that occur as a result of other disorders and illnesses. The patients in this study were in the chronic stages of the injury, and therefore, the results may not generalize to patients in more acute stages.