The evolution and maintenance of large-scale software systems requires first an understanding of its architecture before delving into lower level details. Tools facilitating the architecture comprehension tasks by visualization provide different sets of graphical elements. We conducted a controlled experiment that exemplifies the critical role of such graphical elements when aiming at understanding the architecture. The results show that a different configuration of graphical elements influences program comprehension tasks significantly. In particular, a gain of effectiveness by 63% in basic architectural analysis tasks was achieved simply by choosing a different set of graphical elements. Based on the results we claim that significant effort should be spent on the configuration of architecture visualization tools.