"Let's make a bow. Here, I'll put my finger right there to hold the ribbon, and you tie the bow."

"Okay," she answered cautiously.

Slowly she reached for the slant-cut ends of red ribbon. Holding one between her right thumb and forefinger, the other end between her left thumb and forefinger, she stopped.

She appeared unsure of the next step. Latent muscle memory suggested to her that some time ago she could tie ribbons into bows. But she could not remember ever, actually, tying a bow. She looked at a finished product. She could not reverse-engineer the process of tying a bow (most of us could not do this either).

She watched a happy patient succeed. Her short term memory deteriorated, she could not watch a step and reproduce it.

"We're not in a hurry," I said to her.

"Thank you," she said.

Continuing to grasp the ends of the ribbon, she slowly waved her hands circularly over the spot where my finger held the ribbon in place. Perhaps she hoped the movement might trigger a recollection. It did ...