Hierarchy of the Constituent Characters in Chinese Non-Idiomatic Three-Character Words: An Eye-Tracking Study

The internal structure of Chinese three-character words may guide eye movements, but whether character-level eye movements vary with hierarchical roles remains unclear. In an eye-tracking lexical decision task, we manipulated branching direction and whole-word familiarity in non-idiomatic three-character words (H3CWs), controlled final-character predictability in the primary analyses, and measured skipping probability and fixation durations at the initial and final positions. Initial characters were skipped less often in right-branching than left-branching H3CWs, whereas final characters showed the reverse pattern, consistent with first-level characters being skipped less often at both positions. The predicted low-familiarity branching difference was reliable only for initial-character total fixation duration; first-fixation and gaze-duration contrasts were inconclusive, and no branching-related duration difference was detected for the final character. Higher predictability increased final-character skipping in left-branching but not right-branching H3CWs and was associated with shorter final-character total fixation durations. Apparent final-character familiarity effects were nonsignificant after predictability was controlled. The findings are compatible with structure-sensitive saccade-target selection and a familiarity-dependent pattern in later fixation time. However, because hierarchical role is intrinsically linked to branching and position, and the proposed mechanisms were inferred rather than measured directly, the pattern cannot be attributed uniquely to hierarchical role or a specific processing mechanism.