Understanding software engineers’ behaviour plays a vital role in the software development industry. It also provides helpful guidelines for teaching and learning. In this article, we conduct a study of the extrafoveal vision and its role in information processing. This is a new perspective on source code comprehension. Despite its major importance, the extrafoveal vision has been largely ignored by previous studies. The available research has been focused entirely on the foveal information processing and the gaze fixation position. In this work, we share the results of a gaze-contingent study of source code comprehension by expert (N = 12) and novice (N = 12) programmers in conditions of the restricted extrafoveal vision. The window-moving paradigm was employed to restrict the extrafoveal area of vision as participants comprehend two source code examples. The results indicate that the semantic preview allowed by the extrafoveal vision provides tangible benefits to expert programmers. When the experts could not use the semantic information from the extrafoveal area, their fixation duration increased to duration similar to novices. The experts’ performance dropped in the restricted-view mode, and they required more time to solve the tasks.
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