1 Linguistic units, hierarchies and dynamics of written language production U. Will, R. Weingarten, G. Nottbusch, and Ch. Albes University of Osnabrück Abstract This study reports on the results of five discontinuous typing paradigm experiments in which subjects (native English speakers in experiment 1 and native German speakers in experiments 2 to 5) had to type words presented to them in various modes. In experiment 1 the words were presented in visual form. In experiment 2 words were presented orally and the results are compared with typing following visual word presentation. Experiment 3 compares typing following visual word and picture presentation. In experiment 4 subjects were required to type pseudo-words, whilst in the final experiment the typing responses, following oral and visual word presentation, were delayed by an extended preparatory period. In all experiments we found that the increase of inter-keystroke intervals (IKIs) was highly significant at positions that where either exclusively syllable (S) boundaries or combined syllable and morpheme (SM) boundaries. SM type IKIs are significantly larger than S type IKIs and are influenced by word frequencies, indicating lexical dependencies. SM type IKIs were found to be significantly longer for oral than for visual word presentation. This is taken as an indication that additional processes (phonological-graphemic mediation) are involved in the accessing of graphemic word forms when words are presented aurally. The fact that pseudo-words are also written with increased IKIs at syllable borders indicates that at least one major component of the S-type IKIs is produced by bypassing the lexicon, probably at sublexical levels. The fact that augmented SM and S type IKIs are also found in the delayed typing task indicates that input into the motor system is constituted by sub-word units instead by fully specified words. As SM and S type IKIs reflect influences of different hierarchical levels of language processing, these findings support an associative net architecture of written language production where the peripheral motor system essentially connects at several hierarchical levels with more central units. Introduction Although the present day body of knowledge dealing with the processing architecture underlying language production is considerable, it is mainly concerned with the production of spoken language. This knowledge has been acquired by means of three basic methodological approaches: speech error analysis, reaction time experiments, and the study of clinical–neurological cases (e.g. Butterworth, 1992; Dell, 1986; Garrett, 1975; Levelt, 1989; MacKay, 1987; Stemberger, 1985). In contrast, there have been relatively few studies on written language production and there appear to be two main reasons for this. On the one hand there is the widely held belief that written language production is entirely, or for a large part, dependent on spoken language – a view