Different patterns of mnemonic deficits in two organic amnestic syndromes

A recall and recognition memory study of Korsakoff and post-herpes encephalitis patients employing percentage correct recall and the statisticd′ derived from signal detection theory supports Lhermitte's contention that these two patient groups represent two distinct organic amnesia syndromes. Post-herpes encephalitis patients show little evidence of encoding and storage of information. In contrast recognition memory of Korsakoff and normal control subjects was essentially similar for truly novel information. Recognition memory for English words was markedly impaired for Korsakoff patients and worsened with increased semantic organization of the material. In light of our findings it would seem advisable to utilize homogeneous groups, with respect to brain pathology, when studying memory processes in organic patients.