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Patients with 'dynamic aphasia' exhibit reduced spontaneous speech despite well preserved basic language functions. This disorder may allow insights into the conceptual preparation of messages. Various cognitive approaches have located the patients' impairment at the level of preverbal message generation, including verbal planning, loss of inhibition of lexical concepts, and, most recently, generation of sequences of novel thoughts. We report the case of HK who presented with dynamic aphasia. The study had two goals: first, as HK was assessed over a longer period of time, changes in his performances could be documented which were relevant for the interpretation of the underlying disorder. The present study is the first to document changes across time and improvements of some of the skills involved in language production. Second, further investigations were carried out to clarify HK's underlying deficits. He was unimpaired on a number of 'verbal planning' tasks which argues for the preservation of those specific processes of verbal planning which Levelt (1989) termed 'microplanning'. It is suggested that HK's performance may be best described as an impairment at the level of 'macroplanning'. The deficit may lie in the generation of novel thoughts though minor modifications of this recent approach are being suggested.

One of the major empirical sources of theories of speech production are speech errors in normal speakers. Speech errors occurring during lexicalisation of a concept to be expressed can result in whole-word substitutions that are target related in form and/ or meaning or can appear as nonword productions (neologism). Similar error phenomena have been reported for aphasic patients. The present study describes the aphasic, HZ, who produced mainly form-related word substitutions and neologisms in several single-word processing tasks (picture naming, repetition, and reading aloud). In picture naming, meaning-related substitutions also occurred as well as substitutions that were related both in meaning and form (mixed errors). Three hypotheses of the origin of formal errors were tested: the full interactive activation hypothesis postulating meaning-form interactions, the lexical (form) retrieval hypothesis, and the post-lexical phonological encoding hypothesis. HZ's performance on repetition and reading aloud (tests showed no mixed errors and no effects of imageability and of target frequency on formal errors) failed to support the predictions of the first two hypotheses. However, the phonological encoding hypotheses (enriched by a comprehensionbased editor) could also not account for the data (e.g. for some task-specific asymmetries in the error pattern). Instead, an attempt is made to account for formal and mixed errors by construing word form encoding as an interactively organised component within a two-stage model of lexicalisation. Formal errors are traced back to interactions between lexical forms and sublexical phonological information during the second stage of lexicalisation. Mixed errors occur when lexical forms of the target's semantic competitors are involved in word form encoding.