On the production of word order and the origin of incrementality

One standard explanation for the fluency of speech lies in the assumption that language production works basically like an assembly line — with two significant exceptions. The kind of procedures performed at the various places is transformative instead of additive, and there are devices which enable the system to store a limited number of pieces for later recall and processing. A comprehensive elaboration of this view is Levelt (1989), who claims that the human language processing system is a combination of hierarchical subsystems, each of which is comprised of a number of processing modules. Information is represented by discrete expressions of system specific logical and algebraic languages. Central control has access only to the procedures within the highest subsystem, the conceptualizer, which creates the message. All information flows strictly top-down, and the modules work in parallel getting their input from the preceding module or from the lexicon.