Pathological false recognition and source memory deficits following frontal lobe damage

This study documents a patient (MR) with a demyelinating illness centred on the left frontal lobe who presents with severe memory difficulties in both recall and recognition memory tests. His performance on the latter is characterized by pathologically high false-alarm rates together with unimpaired hit rates. False-alarm rates are not affected by having targets and distracters that are similar to each other (e.g. synonyms) and remain high when inherently unfamiliar stimuli are used (e.g. non-words). This suggests that MR is not over-reliant on familiarity cues. It is suggested, instead, that MR has difficulties in establishing a focused memory description of the target items, such that the memory description that he forms contains features that are common to many items (including distracters) and lacks item-specific distinctive information. A number of lines of evidence are presented which support this interpretation. For instance, orienting instructions (which may alter the featural composition of the target memories) may be used to attenuate false recognition and NIR is impaired at making source attribution judgements (which requires item-specific information) about targets that are correctly recognized.