Investigating Eye Movements in Natural Language and C plus plus Source Code - A Replication Experiment

Natural language text and source code are very different in their structure and semantics. Source code uses words from natural language such as English mainly in comments and identifier names. Is there an inherent difference in the way programmers read natural language text compared to source code? Does expertise play a role in the reading behavior of programmers? In order to start answering these questions, we conduct a controlled experiment with novice and non-novice programmers while they read small short snippets of natural language text and C++ source code. This study is a replication of an earlier study by Busjahn et al. [1] but uses C++ instead of Java source code. The study was conducted with 33 students, who were each given ten tasks: a set of seven programs, and three natural language texts. They were asked one of three random comprehension questions after each task. Using several linearity metrics presented in an earlier study [1], we analyze the eye movements on source code and natural language. The results indicate that novices and non-novices both read source code less linearly than natural language text. We did not find any differences between novices and non-novices between natural language text and source code. We compare our results to the Busjahn study and provide directions for future work.