I now believe that Sam has truly figured out mirrors. A few hours ago, I was holding him up to face a mirror, my cheek pressed against his. He was sucking on his fingers, and then after a moment, without looking away from our reflections, slowly removed his fingers and inserted them into my mouth. Cute kid.
He's doing everything in his power to try to sit up these days. When he's in his carseat, on my lap, or propped on a pillow, he starts lumging his head forward, swimming his arms, and bicycling his legs in the air. He's also getting closer and closer to rolling over, though something always seems to distract him whenever he gets too close.