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 during a target timeframe and at a plurality of instances; receiving, from a content source via a calibration application programming interface, image data including at least one target visual for display via the display device, wherein the image data comprises a video, the at least one target visual traverses a predetermined path comprising target locations during the target timeframe and attracts a gaze of the viewer, and the image data comprises target visual metadata that identifies the at least one target visual in the video, and receiving, from the content source via the calibration application programming interface, a probability that the viewer is gazing at the target locations; without using input from the viewer, identifying within the image data the at least one target visual; without using input from the viewer, using the target visual metadata to identify the target locations of the at least one target visual; comparing the estimated gaze locations of the viewer with the target locations of the at least one target visual at the plurality of instances during the target timeframe; calculating an offset vector for each comparison based on the estimated gaze location and the target location; and calibrating the gaze tracking system using the offset vectors to generate updated estimated gaze locations of the viewer, wherein an offset vector is excluded from the other offset vectors in calibrating the gaze tracking system based on combining the probability with the offset vector exceeding a predetermined threshold offset value. monitoring the estimated gaze location of the viewer using gaze tracking data from a gaze tracking system during a target timeframe and at a plurality of instances; receiving, from a content source via a calibration application programming interface, image data including at least one target visual for display via the display device, wherein the image data comprises a video, the at least one target visual traverses a predetermined path comprising target locations during the target timeframe and attracts a gaze of the viewer, and the image data comprises target visual metadata that identifies the at least one target visual in the video, and receiving, from the content source via the calibration application programming interface, a probability that the viewer is gazing at the target locations; without using input from the viewer, identifying within the image data the at least one target visual; without using input from the viewer, using the target visual metadata to identify the target locations of the at least one target visual; comparing the estimated gaze locations of the viewer with the target locations of the at least one target visual at the plurality of instances during the target timeframe; calculating an offset vector for each comparison based on the estimated gaze location and the target location; and calibrating the gaze tracking system using the offset vectors to generate updated estimated gaze locations of the viewer, wherein an offset vector is excluded from the other offset vectors in calibrating the gaze tracking system based on combining the probability with the offset vector exceeding a predetermined threshold offset value.