How Programmers Read Regular Code: A Controlled Experiment Using Eye Tracking

Regular code, which includes repetitions of the same basic pattern, has been shown to have an effect on code comprehension: a regular function can be just as easy to comprehend as an irregular one with the same functionality, despite being longer and including more control constructs. It has been speculated that this effect is due to leveraging the understanding of the first instances to ease the understanding of repeated instances of the pattern. To verify and quantify this effect, we use eye tracking to measure the time and effort spent reading and understanding regular code. The results are that time and effort invested in the initial code segments are indeed much larger than those spent on the later ones, and the decay in effort can be modeled by an exponential or cubic model. This shows that syntactic code complexity metrics (such as LOC and MCC) need to be made context-sensitive, e.g. By giving reduced weight to repeated segments according to their place in the sequence.