Calibration in eye tracking experiment before each block?

Hi,

I am designing an eye tracking experiment. It has 12 blocks of 6min15s each. I’m wondering if it is necessary to perform calibration & validation for eye tracking before each block? Does anyone know how this could affect data quality?

Thanks!

Without knowing your particular eye tracking system, the general answer to this question:

is always “only if you care about the quality of your data”.

(To be more precise: a new calibration is not always necessary, but a check of the quality of the current calibration almost always is.)