The study examines the effects of using computer delivered Processing Instruction (PI) to teach English reflexives. Thirty intermediate ESL learners participated in the pretest-treatment-posttest study. Participants received the input-based PI activities. Gains were assessed by traditional offline tasks such as sentence interpretation and production tasks as well as a psycholinguistic online task, i.e., a self-paced reading task. Results showed that the input-based Processing Instruction was effective in improving participants' ability to both interpret and produce the target forms as measured by traditional offline tasks. More importantly, the results also suggest that PI was effective as measured by psycholinguistic self-paced online reading tasks.