Linguistic units, hierarchies and dynamics in word typing

Udo Will, Rüdiger Weingarten, Guido Nottbusch & Christian Albes

Abstract: This study reports on five experiments in which English and German participants had to type words presented visually or orally or elicited in a picture naming task. In another experiment subjects were to type pseudo-words, and in the last experiment typing responses were delayed. In all experiments a highly significant increase of inter-keystroke intervals (IKIs) at positions that where either exclusively syllable (S) boundaries or combined syllable and morpheme (SM) boundaries was found. SM-type IKIs are significantly larger than S-type IKIs and 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 are involved in the accessing of graphemic word forms when words are presented orally. The fact that pseudo-words are also written with increased IKIs at syllable onsets indicates that at least one major component of the S-type IKIs is produced by bypassing the lexicon. 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 suggest a processing architecture in which the peripheral motor system essentially connects at several hierarchical levels with central processing units.