A spin on the glass half-full vs half-empty conundrum

Half-Empty vs. Half-Full Glasses: Finger Coordination With "Prehension of Half-Full and Half-Empty Glasses: Time and History Effects on Multi-Digit Coordination" Yao Sun, Vladimir M. Zatsiorsky, and Mark L. Latash, Experimental Brain Research, vol. 209, 2011

Maybe the issue isn't whether the glass is half-empty or half-full, but how you hold it