Methods for tracking the head position of an end user of a head-mounted display device (HMD) relative to the HMD are described. In some embodiments, the HMD may determine an initial head tracking vector associated with an initial head position of the end user relative to the HMD, determine one or more head tracking vectors corresponding with one or more subsequent head positions of the end user relative to the HMD, track head movements of the end user over time based on the initial head tracking vector and the one or more head tracking vectors, and adjust positions of virtual objects displayed to the end user based on the head movements. In some embodiments, the resolution and/or number of virtual objects generated and displayed to the end user may be modified based on a degree of head movement of the end user relative to the HMD.