The calibration and validation screens consist of a number of dots/points, either:
The number of calibration points you use is dependent on the type of experiment you are running.
- Single line reading studies may only use the three points because they only wish to record the x axis (though many are now using 9-point calibrations)
- Visual search and scene perception studies tend to use nine points because they want to record what participants are looking at at any point on the screen
- Multi-line reading experiments that consist of passages of text can use nine, but may benefit from thirteen points in order to make sure that the participant has a good calibration on every line
The calibration process shows each point one at a time and the participant needs to directly fixate each point. The calibration is used to find out where the eye is when looking at each point. This is then extrapolated with an algorithm across the whole scene.
Again, it’s vital to note that a good quality calibration is extremely important.