Many times, people ask why is eye tracking useful beyond the obvious applications of facilitating research and providing user interface for people with disabilities.
One interesting application is in using eye tracking to minimize head tracking latency. Consider the following graph:
The graph shows the position of an eye (black line) and the position of the head (red line), provided in degrees over time. Let's look at some areas of this graph:
- From about 6.5 seconds to 6.7 seconds, we see rapid eye movement from about -5 to +25 degrees. During this period, the head did not move.
- From 6.7 to about 7 seconds, we see the head moving and, in the same time, the eye moving in the opposite direction. Notice that the sum of the head position and eye position is approximately constant throughout this period.
- From 7 to 8 seconds, both the eye and the head are stationary
- From 8 to about 8.2 seconds, the eye moves in the opposite direction
- From 8.2 to about 8.5 seconds, the head follows and the eye reverses direction