Abstract:
Planning to speak is a challenge for the brain, and the challenge varies between and within languages. Yet, little is known about how neural processes react to these variable challenges
beyond the planning of individual words. Here, we examine how fundamental differences in
syntax shape the time course of sentence planning. Most languages treat alike (i.e., align with
each other) the 2 uses of a word like “gardener” in “the gardener crouched” and in “the gardener
planted trees.” A minority keeps these formally distinct by adding special marking in 1 case,
and some languages display both aligned and nonaligned expressions. Exploiting such a contrast in Hindi, we used electroencephalography (EEG) and eye tracking to suggest that this difference is associated with distinct patterns of neural processing and gaze behavior during early
planning stages, preceding phonological word form preparation. Planning sentences with
aligned expressions induces larger synchronization in the theta frequency band, suggesting
higher working memory engagement, and more visual attention to agents than planning nonaligned sentences, suggesting delayed commitment to the relational details of the event. Furthermore, plain, unmarked expressions are associated with larger desynchronization in the
alpha band than expressions with special markers, suggesting more engagement in information processing to keep overlapping structures distinct during planning. Our findings contrast
with the observation that the form of aligned expressions is simpler, and they suggest that the
global preference for alignment is driven not by its neurophysiological effect on sentence planning but by other sources, possibly by aspects of production flexibility and fluency or by sentence comprehension. This challenges current theories on how production and comprehension
may affect the evolution and distribution of syntactic variants in the world’s languages.
