Eye-Tracking Data on Reading English Relative Clauses by Farsi and Dutch Speakers

In an eye-tracking experiment, we explored whether there is a cross-linguistic influence of L1 Farsi and L1 Dutch on the processing of L2 English subject and object relative clauses. Moreover, we assessed whether these L2 learners rely on the morphological cues in that-clause and who(m)-clause conditions or whether they can also process the structural cues in English relative clauses. Forty-two Iranian Farsi-speaking students and twenty-nine Dutch students at the University of Groningen participated in the experiment. They were tested individually in the eye lab at the University of Groningen. Eye movements were recorded using a Tobii 1750 Eye tracker, interfaced with a laptop. The sampling rate was 50 HZ. The materials for this experiment were taken from the items used by Staub (2010) and Staub et al. (2017). The present study used 36 sentences to create four types of relative clauses per item (in total 144 relative clause sentences); subject and direct object relative clauses with either the relative pronoun ‘that’ or the relative pronouns ‘who/whom’. We analysed relative clause sentences in three regions: the embedded noun phrase in the relative clause, embedded verb phrase in the relative clause, and the combined region of these two. For each region, three reading time measures were computed: First-pass reading time (FP), Regression path duration (RPD), and Total reading time (TRT). Statistical analysis was conducted using linear mixed-effects models of the reading times. We used R (R Core Team, 2019) and the lme4 package (Bates et al., 2015) to predict the times of the eye movement measurements based on L1 (Farsi versus Dutch), Clause Type (subject versus object) and Type of Pronoun (that-clause versus who(m)-clause). As random effects, we included intercepts for subjects and items. First, we created a model with the main effects and then compared it with a model with the interaction. In the models, the subject relative was the baseline for Clause Type and that-clause condition was the baseline for the Type of Pronoun. In the case of an interaction of Clause Type and Type of Pronoun, we ran extra analyses to test the effect of Clause Type in the two Types of Pronoun conditions separately.