There is an active debate concerning the association of handedness and
spatial ability. Past studies used small sample sizes. Determining the effect of handedness on spatial ability requires a large, cross-cultural sample of
participants and a navigation task with real-world validity. Here, we overcome these challenges via the mobile app Sea Hero Quest. We analysed the
navigation performance from 422 772 participants from 41 countries and
found no reliable evidence for any difference in spatial ability between leftand right-handers across all countries. A small but growing gap in performance
appears for participants over 64 years old, with left-handers outperforming
right-handers. Further analysis, however, suggests that this gap is most likely due to selection bias. Overall, our study clarifies the factors associated with
spatial ability and shows that left-handedness is not associated with either a
benefit or a deficit in spatial ability