Incremental sentence planning incorporates hierarchical and linear planning for both SVO and SOV languages

Most researchers agree that sentence planning is incremental, but it is unclear how the planning of different sentential elements unfolds before speech onset. This study examined sentence planning in English (SVO) and Korean (SOV) speakers using three images representing either a subject, a verb, or an object/location that were presented in different sequential orders. Participants produced transitive or intransitive sentences. Speech onset latencies and eye movements indicated that both groups of speakers began preparing to produce the subject independently from the verb phrase, although this pattern was limited to participants with shorter-than-average speech onset latencies for their language group. Slower speakers exhibited a sentence type effect, with shorter onset latencies for transitive compared with intransitive sentences. These results suggest that any viable theory of sentence planning should incorporate aspects of both the linear and hierarchical incrementality, taking into account inter-subject variability in planning speed.