The present study investigated how observers move their eyes when tracking multiple moving objects of different identities,and how the eye movements are affected by the perceptual difficulty of the objects.A group of Finnishand Chinese participants were tested in an adapted Multiple-Identity Tracking task.Eight rings moved randomly on the screen,three of which were designated as targets.Each ring had a small gap on it,pointing to a random direction with each target having a distinct gap-orientation.The participants were required to track the targets while they moved and report after the movement stopped the final location of the target with a probed gap-orientation.We manipulated the perceptual difficulty of the objectsby varying the width of the gaps,so that in each trial the gaps were either all narrow or all wide.The results showed that the patterns of eye movements were similar for the Finnish and Chinese participants.During tracking,the observers frequently fixated the targets.Nearly all the targets were fixated at least once.The number of fixations on the targets was more than that on the blank space,with few fixations landing on the distractors.Furthermore,when the gaps were narrow rather than wide,therewere more number of fixations on the targets and more targets were fixated.On the other hand,the number of fixations on the blank was smaller and the duration of fixations on the blank was shorter when the gaps were narrow.The results are consistent with serial models of multiple-identity tracking,by indicating that observers serially shift attention among the objects to refresh the identity-location binding of each target.Moreover,refreshing is affected by object properties:When target identities are difficult to perceive,more refresh time is needed for successful identity-location binding.