mental rotation sport expertise process stages egocentric transformations embodied cognition A selective effect of motor expertise on mental rotation is revealed by a high correlation between the performance of sports experts and ability on a mental rotation task. Evidence is shown by studies involving a spatial factor, such as image interference or a movement constraint. Alternatively, the time constraint, as another performance factor, is considered critical in the effect of sport expertise on mental rotation. Three experiments were conducted to examine the role of time constraints in egocentric mental rotation and the stage performance of athletes (divers) and nonathletes. In Experiment 1, an egocentric mental rotation task in an untimed condition was conducted, and reaction times (RTs) , error rates (ERs), RTs at 0 °, and mental rotation speed were assessed. The results indicated that divers outperformed nonathletes in terms of RT, as well as perceptual and decision stages and rotation stages. Experiments 2 and 3 added a relative time constraint (subtracting 1/2 SD of all the subjects' RT from the M of each group's RT) and an absolute time constraint (subtracting 1/2 SD of all the subjects' RT from the M of all the subjects' RT) to the task, respectively. Superior RT and lower ER were observed for the divers in the time constraint condition. Moreover, the results illustrated that divers were faster than nonathletes in both stages when facing time pressure. In general, the present study has, for the first time, confirmed the role of time in the relationship between sports expertise and mental rotation.