Training a crab to ring a bell..again

Karen’s Blog August 20

A few days ago I finally went on Cornell’s annual alumni field trip to Shoals Marine Laboratory, on an island off the coast of New Hampshire. Met a lot of nice and interesting people on the boat trip over—Hi Sue, hi Bob, Hi Louise and Stefan and Hannah, hi, Fern. We saw lots of sea birds and seals. We toured the island, watched the bird banding, visited labs, inspected some (very tidy) student dorms.

Cornell offers college-credit courses all summer; students come over for two week stays or longer. At lunch time I sat down with a bunch of students. We all started talking. The girl next to me looked at my name tag, startled, and said “Are you Karen Pryor?” Yes. She was very excited. “Your book changed my life.” Hmm. Too young for it to be Nursing Your Baby; she must mean Don’t Shoot the Dog; the new book’s only been available three weeks.

No, Lily Strassberg meant Reaching the Animal Mind, and got a jacketless and already well-used copy out of her back pack for me to sign.

Lily is 17. She has been clicker training dogs since she was ten, and now teaches public obedience classes. She read my story in Chapter 1 about training a hermit crab to ring a bell. So, for her class research project last week at the marine lab, she set out to train a crab to ring a bell. Her professor doubted it would work, but she was so excited about it, he let her try.

Lily collected some of the local hermit crabs around the island. They were very small and timid so she used the local green crab Carcinus maenas instead. (These are pointy-shelled Portunid crabs, like the blue crabs we eat on the East Coast, only of course they are green not blue.)

Lily used the same reinforcement procedure I did--feeding with forceps, using the movement of the forceps as the click. She shaped the behavior of shoving a hanging weight with a claw, an improvement over my more complicated job of pulling a string down.

Just to be safe, in spare moments across two days she trained two crabs, Crab A and Crab B, Abby and Bertha. She took good and thorough data, photographs, and video too. When she presented her project, the other students burst into applause. The professor said her study was ‘practically publishable.’ When the experiment was over, Lilly released Abby and Bertha back to the ocean in the same place where they were collected.

I was thrilled. So, apparently, were the crabs, and here’s why I think that.

For each session the crab had to be moved into a small experiment tank with a grid drawn on the floor (to measure exactly how far the crab came toward the target each time.) At first the crabs were hard to catch, and struggled mightily when lifted into the air. But soon, they got it—Oh, I’m flying to the place where I train them to feed me delicious stuff—and they just held still to be picked up by the shell, and relaxed completely in the air, legs hanging down calmly. Now I ask you: isn’t that cool? Clicker-wise ‘operant’ crabs?

What were the chances that out of 100 people or more in the room I would sit down next to Lily?

You will be hearing more about Lily, I bet.