Abstract: The filter/flow model is a graph-based query visualization capable of representing arbitrary Boolean expressions. However, the resulting graphs quickly become large and hard to handle when representing complex search queries. We developed an extended filter/flow model that allows the display of complex queries in a more compact form. This paper reports on a user study we conducted to evaluate the readability of the extended model. The results indicate that it is as readable as the basic one and slightly preferred by users. Therefore, we regard the extended model as a good alternative to the basic one, especially when it comes to the visualization of complex queries.