Sentence Comprehension under Syntactic Ambiguity: A Study of Processing Speeds in Native and Non-native English Speakers

This comparative study explores how native and non-native speakers of English process, comprehend, and react to three types of sentences, namely garden-path, ungrammatical, and grammatical sentences. While both English and German are “diachronically related Germanic languages” (Kilborn, 1989, p. 4) and share structural similarities, they differ in certain constructions that may affect sentence processing. As an underexplored field of research, this study sheds new light on the difficulty that native and non-native speakers of English have in processing and understanding garden path sentences and ungrammatical sentences, as the syntactic representation of German subjects is not quite like English native speakers.

Twenty-four participants (12 native English speakers and 12 German non-native speakers of English) took part in a self-paced reading task developed in PsychoPy. Native speakers were recruited from the American community in Germany (mean residency = 16.81 years), and non-native participants were advanced English speakers with academic backgrounds in English and American Studies at Chemnitz University of Technology. Their L2 proficiency was assessed via university English grades and a biographical questionnaire, indicating an early onset of English learning (M = 7.92 years, SD = 0.29) and frequent academic use.

The study’s stimuli included:

1) Garden-path sentences involving subject/object ambiguity (e.g., While the friends hugged the pet was lying on the mat.) and noun/verb ambiguity (e.g., The youth fashion patchwork from cloth); 

2) Ungrammatical sentences with syntactic violations such as altered word orders (e.g., in verb, noun/ adjective, and preverbal subject position) or omitted modal verbs (e.x., in questions and imperatives);

3) Well-formed grammatical sentences. 

All sentences were authored by the researcher and further validated by English native speakers and linguists to ensure appropriateness. They were carefully drafted to highlight and contrast structural differences between English and German. Participants were instructed to read each sentence and judge its comprehensibility. Garden-path sentences were followed by comprehension questions to measure the accuracy level of their responses. It incentivized the participants to read the sentences carefully and reply attentively, not by chance. 

A mixed between-within subjects ANOVA revealed no significant difference between native and non-native groups in overall performance (F(2,21)=1.90, p=0.175, η² = 0.15). However, within-group comparisons showed significant processing differences across sentence types. Bonferroni post-hoc tests confirmed that garden-path sentences elicited significantly longer reaction times than both ungrammatical (p=0.001) and grammatical sentences (p=0.001), while the difference between ungrammatical and grammatical sentences was not significant (p=0.51).

In sum, the findings suggest that garden-path items pose substantial processing challenges for both groups, though not necessarily more for L2 speakers. These results contribute to the limited body of research comparing real-time sentence processing across typologically related but structurally divergent languages, both between-and within-groups.