Experiment to observe default choice

H: Hold this cardboard in front of one eye, and look through the hole in it at those keys on the wall there.

*I hold it up on my left eye, and close the right one.*

Me: Do you want me to read the text on the keys?

H: No, that’s it. Just wanted to check which is your preferred eye.

I loved the simplicity of this experiment :)

She gave me a deliberately vague instruction. This let my mind fill in the rest based on its default behaviour. She just wanted to observe that default behaviour.