I assume it's a running success rate.

It's making a (hidden) prediction about what key you'll press, and it's displaying the number of times it was correct over all your key presses.

So, the more you've pressed the keys, the less each successive press will change it's overall success rate.

It isn't telling you the odds of what you'll do next. It's telling you how often its hidden predictions been right so far. So if you've hit 100 keys, and it secretly guessed 75 of them right, it will display 0.75. The more you play, the more slowly this number moves, because each additional guess has a smaller effect on the overall average.

>The more you play, the more slowly this number moves, because each additional guess has a smaller effect on the overall average.

Not exactly, seems to be a running average with a specific window.

I was able to get it to slowly go down, more or less, by switching things up whenever I saw the percentage start increasing. Usually kept doing the same key or pattern as long as it went down and as soon as it started ticking up I switched it.

A couple things I did to get it down to ~.44 Press based on random environmental input (woman's voice on tv = f, man's voice = d, while flipping channels). Do it very quickly, while paying attention to something else that utterly absorbs your attention, and don't look at the meter.