1. A method for calibrating an estimated gaze location of a viewer of a display device, the method comprising: monitoring the estimated gaze location of the viewer using gaze tracking data from a gaze tracking system; receiving image data for display via the display device; without using input from the viewer, identifying within the image data at least one target visual that may attract a gaze of the viewer and a target location of the at least one target visual; comparing the estimated gaze location of the viewer with the target location of the at least one target visual; calculating an offset vector based on the estimated gaze location and the target location; and calibrating the gaze tracking system using the offset vector to generate an updated estimated gaze location of the viewer.