Zusammenfassung
The present dissertation investigated the mechanisms of incremental sentence
processing in Japanese, a language with word order freedom (scrambling)
and argument omissibility (pro-drop). To this avail, four event-related brain potential
(ERP) experiments were conducted employing simple transitive sentences, with
Experiments 1 and 2 investigating the influence of prosodic information and case
marking on the processing of scrambled sentences, and Experiments 3 and 4 examining
the processing of pro-drop sentences in isolation and embedded in linguistic
contexts. The neurophysiological data pattern observed across experiments strongly
suggested the separation of a phrase structural, interpretive, and discourse level
of representation, with a universal processing principle called Minimality applying
at all three levels (requiring minimal one-argument structures, minimal intransitive
events with only one participant, and minimal discourse representations without
redundant referents, respectively). Crucially, depending on the level of representation,
violations of the Minimality principle were reflected in different kinds of
independently varying ERP signatures: A one-argument phrase structure could not
be maintained whenever an initial object signaled a scrambled (OSV) sentence, engendering
a scrambling negativity in comparison to initial subjects as a result. If,
however, the prosodic information or the case marking on the initial object allowed
an alternative one-argument (subject-drop, OV) reading of the sentence, no such
effect was observable. Regardless of prosodic or case marking information, an N400
always arose at the position of the second argument of canonical (SOV) sentences
in comparison to scrambled (OSV) sentences, reflecting the extension from an intransitive
to a transitive event interpretation that became necessary at this position.
Finally, at the discourse level, Minimality effects became evident in the variations
of a positivity effect arising at the position of the verb of subject-drop (OV) and
object-drop (SV) sentences in comparison to canonical complete (SOV) sentences.
This component, which was taken to reflect the inference of the missing discourse referent
from outside the sentence, was particularly pronounced when a new discourse
referent needed to be established, i.e. when the pro-drop sentence was presented
in isolation or when the preceding context did not provide a suitable referent. An
additional sensitivity of the positivity effect to the amount of referential competition
further supported a conceptualization of Minimality as a subcase of a more general
processing principle calling for maximally distinct representations at all three levels.
In sum, the present findings suggest that a Minimality/Distinctness based account
incorporating several levels of representation qualifies as a promising approach to
deriving the neurocognitive signatures of incremental sentence comprehension across
languages.
