Speech error data and empirical studies suggest that the scope of planning is larger for semantic than for phonological form representations in speech production. Previous results have demonstrated that some patients show dissociable impairments in the retention of semantic and phonological codes. The effect of these STM deficits on speech production was investigated using a phrase production paradigm that manipulated the semantic relatedness of the words in the phrase. Subjects produced a conjoined noun phrase to describe two pictures (e.g., "ball and hat") or produced the same phrases in response to pairs of written words. For the picture naming condition, control subjects showed an interference effect for semantically related pictures relative to unrelated pictures. This interference effect was greatly exaggerated for two patients with semantic short-term memory deficits but not for a patient with a phonological STM deficit. For the written words, control subjects showed a small facilitatory effect for the onset of phrases containing semantically related words. One of the patients with a semantic STM deficit who was tested on picture naming was also tested on these materials and showed a small facilitatory effect within the range of controls. The findings support the contention that speech planning is carried out at a phrasal level at the lexical-semantic level and that the capacities that support semantic retention in list recall support speech production planning.

Patients with semantic STM deficits have difficulty comprehending sentences that require the retention of several lexical-semantic representations prior to their integration into higher-level propositions (Martin, 1995: Martin & Romani. 1994). In Experiment 1, patients with a semantic retention deficit had difficulty with the same type of constructions in speech production, namely noun phrases with one or two prenominal adjectives. Their performance improved when they could produce the nouns and adjectives in sentence form, which placed smaller demands on lexical-semantic retention. In Experiment 2 these patients were better able to produce syntactically complex sentences than the prenominal adjective phrases having an equal number of content words, indicating that the findings in Experiment 1 could not be attributed to syntactic complexity. These patients produced more pauses in the sentence constructions in Experiments 1 and 2, suggesting that the timing of such productions is abnormal. In contrast, patient EA, with a phonological retention deficit, performed better than the patients with a semantic retention deficit on the AN phrases despite having a smaller STM span. She showed no significant benefit of producing sentence compared to phrase constructions, and also made fewer and shorter pauses than the other patients. These findings support the multiple capacities view of verbal working memory and suggest that the same semantic retention capacity used in language comprehension is used in speech production.

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.

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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 longterm memory.Historically, the "modal" model of memory (e.g., Shiffrin & Atkinson, 1969) postulated a separation between short-term memory (STM) and longterm memory (LTM). This model also postulated that information was held in STM in order to be transferred to LTM. The notion of a connection between short-term retention and long-term learning goes back to Hebb's (1949) hypothesis of reverberating cell assemblies. In Hebb's view, the simultaneous presentation of two or more stimuli would result in the firing of an assembly of cells representing the different stimuli, with activation reverberating for some time after the stimuli were removed. The repeated presentation of the same stimuli would reactivate the same cell assembly, and over time structural changes would occur that would facilitate transmission among the components of the cell assembly. The reverberation could be seen as an instantiation of STM and the necessity of this reverberation for structural changes as implying that reverberation in STM is a necessary component of the formation of long-term memories. Recent neurophysiological work is broadly congruent with Hebb's hypthoses (e.g., Hoang, Nguyen, Abel, & Kandel, 1996). Although there have been challenges to various aspects of the modal