Retrospective confidence judgements made by adults with traumatic brain injury: relative and absolute accuracy

Eighteen adult survivors of moderate or severe traumatic brain injury (TBI) and 18 controls studied and were tested on two lists of noun-pairs, and made item-by-item retrospective confidence judgements (RCJs) of their answers using a Likert scale. For both groups, correlations between RCJ ratings and recall were extremely high, indicating that survivors of TBI were as accurate as non-injured controls when comparing their confidence in one answer to another. However, as groups, survivors of TBI were over-confident and control participants were under-confident, but only when uncertain as to the accuracy of their answer. Recall errors of 'interference' were analysed post-hoc. Survivors of TBI displayed higher confidence in interference errors than in non-interference errors, while control participants did not. These results are discussed within the context of self-monitoring by clinical and non-clinical populations. The importance of both relative and absolute measures of metamemory accuracy is highlighted.