When you ignore what you see: How to study proof-readers' error in pseudocode reading.

When reading algorithms, expert programmers are often able to predict what the code should contain. On occasion, however, this ability may result in so-called proof-readers’ errors, where the visual input is ignored and programmers process the code based on their own predictions. The goal of this study is to gain initial understanding of how proof-readers’ errors are reflected in eye-movement parameters of an experienced programmer, and to search for parameters that may be indicative for proof-readers’ errors in pseudocode reading. We applied a case-study approach to test the hypothesis that cognitive processing of notation, when read both with and without proof-readers’ errors, results in similarities in terms of selected eye-movement measures. However, our experienced programmer turned out to become a critical case falsifying this hypothesis. In general, case studies with expert programmers are a rather novel approach for eye-tracking studies of programming, even though single cases of experts’ eye movements are actively applied for the development of eye movement modelling examples. This study therefore also points to the importance of regarding expert examples not just as representatives as ”expert reading” in general, but also as unique cases worth a closer investigation.