We varied the spatial features of adjunct displays that depicted a complex scientific system (i.e. human circulatory system). University students (n = 47), who were assigned randomly to a display condition before reading, selected relevant information from the text and wrote it (a) next to a list of definitions (list condition), (b) inside boxes organized to coincide with the sequence of blood flow (chart condition), or (c) on a picture of the heart (pictorial condition). Students in the chart and pictorial conditions had higher scores on 2 learning tests. Results supported the "nonequivalence hypothesis", which states that a spatial display can promote learning more effectively than a list because a display's nonverbal (e.g. spatial) features explicitly depict relationships among a system's components. The results have implications for science educators.