The Mental Rotations Test (Vandenberg & Kuse, 1978) consistently produces large sex differences favoring males (Voyer, Voyer, & Bryden, 1995). This test requires participants to select two of four answer choices that are rotations of a probe stimulus. Incorrect choices (i.e., foils) are either mirror reflections of the probe or structurally different. In contrast, in the original mental rotation task (Shepard & Metzler, 1971) participants judge whether two stimuli are the same but rotated or different by mirror reflection. It was hypothesized that the large sex difference in the Mental Rotations Test emerges as a result of males noticing and capitalizing on the orientation independent features of structurally different foils. Two experiments indicated greater accuracy and faster reaction times for structurally different compared to mirror trials for both sexes. A significant male advantage in accuracy was found for both trial types. Males and females did not differ in reaction time for either trial type. Although no evidence was found to suggest that differences in capitalizing on an orientation independent strategy accounts for the large sex difference, results suggest that the mental rotation process is not the only source of the sex difference in these tasks.