The anterograde and retrograde retrieval ability of a patient with amnesia due to encephalitis

A patient with amnesia due to encephalitis was previously described in 1976 as having normal short-term memory and an intact ability to perform semantic analysis. Despite this ability, his retention beyond the limits of short-term memory was nearly nil. The present investigation sought to evaluate more completely the nature of this patient's retrieval deficit using a series of paradigms developed subsequent to his initial testing. Once again it was discovered that while his intact analytic abilities allowed retention of material in working memory, as soon as that working capacity was exceeded, retrieval of information became nearly impossible. It became apparent that the patient could not discriminate between a cue's most recently analyzed associate and the strongest existing associate to that cue in his semantic hierarchy. An analysis of his retrograde memory ability showed that he could retrieve almost no real episodes of either a public or private nature from his past. Instead, he seemed to rely on generalizations from his semantic memory to reconstruct "probable" events.