Morphemes in written word production

8th International Conference of the European Association for Research on Learning and Instruction (EARLI) Writing Special Interest Group (SIG): Writing02, 10th to 13th July 2002, Staffordshire University, Stafford, UK, Vortrag in der AG2 "Cognitive processes in writing".

Guido Nottbusch, Angela Grimm & Rüdiger Weingarten (University of Osnabrueck): Morphemes in written word production.

Abstract: In previous studies we found that the time course of typing in written language production correlates closely to the linguistic structures within words: The duration of inter-keystroke intervals (IKIs) was significantly longer when a syllable commenced with the following key (S-type) and was longest when the key at the same time marked the beginning of a new morpheme (SM-type). The latter were influenced by word frequencies, indicating lexical dependencies. These effects were stable under various conditions (written, oral and pictorial stimulus) and in different languages (English, German). Therefore we conclude that the input into the motor system is composed of sub-word units instead of fully specified words.
In the present study we concentrate on the SM-type IKIs and explore the influence of two aspects: In Experiment 1 we investigate possible timing differences in the access of different types of morphemes. Under the assumption that the duration of the IKI preceding a combined syllable and morpheme boundary (SM) is affected of its lexical access, we compared German words (a) containing prefixes (e.g. <vor-verkaufen> [to sale in advance] and compounds (e.g. <Natur-volk> [primitive race] and (b) words containing suffixes (e.g. <Heiter-keit> [cheerfulness]) and again compounds (e.g. <Wasser-krug> [water jug]). Differences in timing at the start of stem morphemes and suffixes were significant, the latter being initiated faster. The slight differences between the initiation of prefixes and stems were nonsignificant. Our proposal to explain these results is as follows: For prefixes a following unit is obligatory. ( Prefix+[Prefix+Stem] ). The access to prefixes seems to be influenced by frame information of the following unit containing a stem. For suffixes constraints are different: A following unit after a suffix is only optional. (This can only be another suffix or a new frame containing a stem.) ( [Stem+Suffix] ) In the case of Stem+Suffix constructions the access to the suffix is faster - no further information is needed.
In our second Experiment we examine the recent results concerning the differences between absolute and relative word frequencies (see Hay, 2000) adapted to the field of written word production. Therefore we selected German compounds and prefixed words that have (a) a high whole word frequency but low base (stem) frequency (e.g. <Gast-geber> [host]), that are possibly accessed in a holistic fashion and contrast the measured SM-IKIs with (b) words with a low whole word frequency but a high frequency of the root morpheme beginning at the SM-boundary (e.g. <Blut-gruppe> [blood group]), probably composed on-line. In Experiment 2 the overall comparison between higher whole word and base frequency did not lead to significant differences. The difference becomes clearer if the frequency levels of the items are taken into account: Significantly increased latencies at morpheme onsets were found only in low frequency items with relatively higher base frequency. This is interpreted as an effect of compositional word production. There may also be compositional processes in high frequency items with higher base frequency. Possibly in these cases the compositional processes are too fast to be detected within the time course of word writing.