Impaired memory for scenes but not faces in developmental hippocampal amnesia: a case study

Abstract

Item recognition for unfamiliar faces and scenes was tested in Jon, who has developmental amnesia resulting from bilateral hippocampal pathology. Performance and confidence judgements in healthy adults showed that both tests were equated for difficulty and had similar receiver operating characteristics (ROCs). Jon's performance on the faces test was indistinguishable from the controls, in both sensitivity and the shape of the ROC curve. In contrast his performance on the scenes test was markedly poor, and his ROC was inconsistent with both a standard dual process (DP; recollection and familiarity) model and an unequal variance signal detection model of recognition memory. Jon's data were as well fitted as controls' data by a DP model that included two recollection parameters, but required counter-intuitive parameter values corresponding to normal recollection and impaired familiarity, which likely reflect an idiosyncratic use of confidence judgements when his memory for the material is weak. The results highlight a limitation in using ROCs to estimate recollection and familiarity in patients who may have developed compensatory strategies for material that they have difficulty remembering (scenes, but not faces in this case). Overall, these data are difficult to reconcile with domain-general accounts of the hippocampal role in memory, including dual process models and the declarative model. Instead, the data indicate that the hippocampus plays a preferential role in the processing of topographical memoranda over faces memoranda.