Unconscious processing in memory recall. A study of three amnesic patients.

The sudden resurgence of precise information some time after the failure of its recall (memory block) suggests the intervention of unconscious processes. In normal subjects the experimental demonstration of such processes meets with methodological snags. They are avoided in patients with a pure amnesic syndrome because retrograde amnesia produces many instances of missing memories, while anterograde amnesia prevents the patient from consciously thinking about it. Three patients with a pure amnesic syndrome were submitted to 4 interviews over 12 days on 3 topics concerning places and itineraries that were very familiar before the disease, and a shocking event of their life. Retrieved memories were compared to those of normal matched subjects. The results showed a dramatic increase for memories of places and itineraries over sessions, and the absence of improvement of autobiographical memories. These findings underline the role of the activation of unconscious processes in recall and the different status of semantic and episodic memory.