I'm learning piano at an early stage - playing Grade 1 level stuff I suppose. However I did classical guitar as a kid and play chords in a band so my general musicality is higher than that.
The pieces being so simple, I fairly quickly memorise them without trying to, before I can actually play them fluently. I don't normally look at the keyboard when playing pieces but I found that if I know a piece by heart, if I do look at what my hands are doing it makes me mess up much more than if I stare into the distance. I would've expected it would help me play, not hinder me.
Is this common and can anyone explain why it would be the case... and if it matters? By contrast if I'm playing chords rather than a piece, I always look at the keys because I can't find the notes reliably enough as my hands move around!