Although demonstrations play a central role in teaching and learning chemistry, the effects of concrete setup principles have rarely been subject to systematic empirical studies. According to the left-to-right principle, the educator should begin with the first step of a reaction in the upper left part of the setup and then place the following apparatus in the lower right. Using data from an experimental eye-tracking study on students' visual attention that was published in the "Journal of Chemical Education," we reanalyzed eye-tracking in order to find out whether eye-movements are influenced in a manner that supports a setup according to the left-to-right principle. On the basis of a pattern analysis, the results show that left-to-right patterns generally appear significantly more often within the data than right-to-left patterns. Although the left-to-right demonstration does not seem to systematically include more left-to-right patterns, it is associated with a decrease of right-to-left patterns. Accordingly, a right-to-left setup seems to add more eye-movements that do not follow the logic of the demonstration. We discuss these findings with regard to their importance for educators and new perspectives on future chemistry demonstrations research.