Mental rotation tests (MRTs) have previously shown one of the most prominent sex differences in cognitive psychology, marked by a large male performance advantage. However, debate continues over the reasons for these sex differences. Previously, we used pupillometry to demonstrate sex differences in the cognitive effort invoked during the original MRT. Here, we evaluated the magnitude of sex differences during performance on a computerized version of the Vandenberg and Kuse MRT. Secondly, we examined whether fixation metrics could illuminate strategy use by participants. Finally, we used pupillometry to investigate whether cognitive effort differed between sexes and trials of different difficulty. While our results demonstrate no performance differences between sexes on the computerized MRT, fixation patterns provided evidence that gaze strategy was associated with performance on different parts of the test. Moreover, we show the cognitive demand of the V&K MRT, evidenced by large task dependent increases in participants' pupil diameters.