The present study combined the approaches of multimedia learning and of comparative visual search (Hardiess, Gillner, & Mallot, 2008) in order to analyse the processing of spatially separated information. Participants were asked to compare two depictions of a mechanical pendulum clock to detect no, one, or two differences between them. The spatial distance between the two depictions was varied, and participants received either stimulus-related information about the functionalities of pendulum clocks or stimulus-unrelated information about the design of cuckoo clocks. The study demonstrates a trade-off between gaze movement and working memory use. We observed fewer gaze shifts with increasing distance between the pictures, suggesting higher working memory use. The findings indicate that the distance between two pictures, domain knowledge and visual working memory span are important factors that determine memory load required for processing split information sources. Copyright © 2012 John Wiley & Sons, Ltd.