Sources of relative clause processing difficulty: Evidence from Russian

- Expectations and memory-based integration affect incremental RC processing.
- Structural asymmetries do not influence the online processing of RC sentences.
- Structure and NP similarity affect the late-stage comprehension of RC sentences.

This study investigates the sources of processing difficulty in complex sentences involving relative clauses (RCs). Self-paced reading and eye tracking were used to test the comprehension of Russian subject- and object-extracted RCs (SRCs and ORCs) that had the same word-order configuration, but different noun phrase (NP) types (full NPs vs. pronouns) in the embedded clause. In both SRCs and ORCs, this NP intervened between the modified noun and the RC verb. A corpus analysis and acceptability rating experiment indicated different frequency/preference profiles for this word order depending on RC type and embedded NP type. In line with these profiles, processing difficulty was revealed early in the embedded clause for less frequent/dispreferred constructions. Later in the embedded clause, the processing of the RC verb was comparable for both SRCs and ORCs when the same number of NP arguments was available for integration. While there were no indications of an ORC penalty at or after this verb, late-stage comprehension difficulty was found for full-NP ORCs, but not for their pronominal counterparts, suggesting that similarity-based interference in combination with ORC structure influences the overall comprehension of these sentences. Taken together, these findings support a hybrid model under which independent sources of processing difficulty affect different stages of RC comprehension.