Effects of Non-linguistic Factors on Frequency Analyis of English Relative Clauses

Previous corpus studies (Roland et al. 2007, 2012; Reali & Christiansen 2007) have accounted for the processing differences between object-extracted relative clauses (ORCs) and subject-extracted relative clauses (SRCs) by examining the relative-clause types that occur more frequently in corpora. This paper demonstrates that this approach faces non-trivial problems because the relative frequencies of ORCs and SRCs can vary considerably across corpora owing to non-linguistic factors such as modes and genres. SRCs appear more frequently than ORCs in an argumentative-essay corpus, whereas ORCs appear more frequently than SRCs in a spoken corpus and a narrative-essay corpus where the first-person or/and second-person pronouns are used extensively. The frequency of SRCs increases significantly in an essay corpus in which the writing topics are closely related to animate entities. Therefore, non-linguistic factors of corpora must be considered when analyzing the frequencies of ORCs and SRCs in corpora.