Disordered memory awareness: recollective confabulation in two cases of persistent déjà vecu.
We describe two cases of false recognition in patients with dementia and diffuse temporal lobe pathology who report their memory difficulty as being one of persistent déjà vecu--the sensation that they have lived through the present moment before. On a number of recognition tasks, the patients were found to have high levels of false positives. They also made a large number of guess responses but otherwise appeared metacognitively intact. Informal reports suggested that the episodes of déjà vecu were characterised by sensations similar to those present when the past is recollectively experienced in normal remembering. Two further experiments found that both patients had high levels of recollective experience for items they falsely recognized. Most strikingly, they were likely to recollectively experience incorrectly recognised low frequency words, suggesting that their false recognition was not driven by familiarity processes or vague sensations of having encountered events and stimuli before. Importantly, both patients made reasonable justifications for their false recognitions both in the experiments and in their everyday lives and these we term 'recollective confabulation'. Thus, the patients are characterised by false recognition, overextended recollective experience, and recollective confabulation. These features are accounted for in terms of disrupted control of memory awareness and recollective states, possibly following brain damage to fronto-temporal circuits and we extend this account to normally and abnormally occurring states of déjà vu and vecu and related memory experiences.