Absentmindedly

He did it absentmindedly.

Even though the student appeared to be focused, he was actually absentmindedly gazing at the ceiling.

She agreed to it all, more or less absentmindedly, as she sat looking into the moonlight, and the day that had begun so stormily ended in kindness between them.

Across the aisle, she was absentmindedly fiddling with a loose piece of yarn that had unraveled from her sweater, wrapping it around her finger the same way Derek was wrapped around her finger. And she didn't even know it. Hoo-boy. She killed him.