Unconscious learning during anaesthesia.

Forty-three surgical patients were, during general anaesthesia, presented (via headphones) with either statements about common facts of some years ago (group A), or new verbal associations, i.e. the names of fictitious, nonfamous people (group B). None had any recall of intra-operative events. In a postoperative test of indirect memory, patients in group A answered more questions about the 'common facts' correctly than those in group B (p < 0.005), which reflects the activation of pre-existing knowledge. Furthermore, patients in group B designated more 'nonfamous names' as famous (thus falsely attributing fame) than patients in group A (p < 0.001), which demonstrates that information-processing during anaesthesia can also take place as unconscious learning.