Item priming and skill learning in amnesia.

This study employed a semantic decision-making task to examine both item priming and skill learning in amnesia, which traditionally have been demonstrated with separate tasks. Fourteen amnesic patients of mixed etiologies and 14 normal control subjects judged whether words represented animate or inanimate objects. One list was presented repeatedly on four continuous blocks of trials, and a new list was presented on the fifth block. For both groups, decision times decreased significantly from Block 1 to Block 5 (indicating skill acquisition) and increased significantly from Block 4 to Block 5 (indicating item-specific learning). The amnesic patients demonstrated a normal rate of skill learning, but a reduced magnitude of item priming. As expected, the amnesics had significantly impaired explicit memory of the implicitly learned items, as measured by recognition accuracy. The results suggest that both implicit and explicit learning of individual items is impaired in amnesia, despite normal semantic skill learning.