Dissociable components of short-term memory and their relation to long-term learning.

Short-term memory (STM) includes dissociable phonological and semantic components (R.C. Martin, 1993). Previous findings indicate that phonological STM capacity supports learning of novel phonological forms, such as new vocabulary (e.g., Baddeley, Gathercole, & Papagno, 1998). It was hypothesised that semantic STM capacity would support the learning of novel semantic information. Five aphasic patients were tested who demonstrated deficits in the short-term retention of either phonological or semantic information. Four of the five patients demonstrated learning deficits in a paired associate paradigm that corresponded to their STM deficits. One patient with a severe deficit in phonological STM but a better-preserved ability to retain semantic information showed better learning of new semantic information than new phonological information. Three patients with a greater deficit in semantic than phonological STM showed the reverse. A fifth patient with a severe semantic STM deficit failed to show learning for either type of material. Results suggest that the semantic and phonological components of STM are essential for the long-term learning of corresponding representations in long-term memory.