Posner cueing task error

There are two variables ''none" among the valid and invalid trials in the “is_valid” column. What does it imply and how do i explain it?

Please could you explain your question in a bit more detail?

I’m assuming that you have variables with a value of none rather than variables called none.

Sorry for the late response!
Screenshot (16)

Probably, yes, I’m not very familiar with the terminologies. This is what it looks like. It’d be very helpful if you could point out the reason behind it or a way to fix it/explain it.

I think that None refers to there being no cue on those trials rather than a valid or invalid cue.