It's a computer program, it checks his work. He has to press the key within a time period. It's like Mavis Beacon for typing.
I suggest this. Always play low notes with left hand 5, always place high notes with left hand 1, if the next note is higher shift fingers (hold the note and move a different finger onto it. As much as you can don't look at the keyboard.
I appreciate that it's a computer programme, but if you need verification to find out if you were right or not, you need a method for being certain - not external verification. When I read a note, I either know that I know it or I know that I don't know it. If I'm halfway, I'll assume that i don't and quickly use a method to calculate it. When sight reading under pressure, you occasionally have to take some guesses, but it's more about the sheer density of notes. It's not that any individual note is hard to read, but rather that there's too much going on to rigorously double-check them all. I don't encounter individual notes where I'd need something to tell me if I'm right or not. The only exception to certainty of recognition is with extreme leger lines. Again, I never guess on a whim though, unless I absolutely have to press on. If I know it, I play it with certainty. If I don't, I count up the letters in thirds or compare to a near by note that I know for definite. Then I know for sure what it is.
I appreciate that this is because I have experience, but the best way to get the finest experience is to stop guessing, be your own marker and never proceed without utter certainty (except in a very small minority of pressured reading practise). Until you're totally one hundred percent certain of the notes, never have a go on a mere inkling. Find a quick but infallible method instead. Only when any single note (other than those involving four or more leger lines) is known for certain at first sight, is there any need to pressure yourself. It just ruins the foundations to rush things that you haven't been double checking for yourself. stage one is to be capable of top quality self observation . Only with that foundation set in stone is it time to throw caution to the wind and start taking gambles.