Abstract: The processing asymmetry effect of Subject\object relative clauses is a phenomenon across many languages. Studies have found two important factors contributing to this effect: cognitive resources and syntactic structure. The present paper analyzed this phenomenon from the three following perspectives: 1) its universality and particularity in Indo-European and non-Indo-European languages, revealed in the language by adults, children, and aphasics; 2) different models of the processing asymmetry effect, including the syntactic role theory, filler-gap dependency theory, active-filler strategy, noun phrases accessibility hierarchy theory and similarity interference theory; 3) ERPs (event-related potentials) components and brain activations. Finally, “fluid mark theory” based on our studies and others was constructed to account for sentence processing, and future research directions about the issue were pointed out.

Key words: subject relative clause, object relative clause, processing asymmetry effect