First, we tried sitting our hyenas down and giving them IQ tests. Unfortunately, they couldn’t hold the pens, and they ended up eating the test booklets. Back to the drawing board.
Seriously though, in order to be effective, our test had to meet a few criteria. First of all, it had to be hyena-proof. It needed to be something our hyenas couldn’t destroy, consume, or drag away.
The test also had to be something that, even with their limited dexterity, hyenas could manipulate in some way to “solve.”
Finally, the test had to represent a “novel task,” which is scientist-speak for “a challenge the hyenas have never seen before.” This way, we know the hyenas aren't just relying on some skill they already have.
Luckily, clever grad student Sarah Benson-Amram came along and developed a test that meets all these criteria. Called a “puzzle box,” it’s based on an invention by psychologist E.L. Thorndike.
Essentially, it’s a big box made of rebar (and when I say “big”, I mean “BIG…” this thing weighs about 75 pounds). The box has a swinging door that closes and locks with a sliding latch. We put a piece of meat inside the box as an incentive, close and lock the door, and present it to a hyena. Their task is to figure out how to get to open the box and get to the meat inside. Just like a Rubik’s cube or Sudoku puzzle is a brainteaser for us, the puzzle box is a way to test hyenas’ problem-solving abilities.
My favorite thing about watching hyenas interact with the box is the multitude of strategies they employ. Some bite the box; others dig underneath it. A few flip and tumble the box. Some decide that an aerial view will help, so they get on top of the box and peer down. Many hyenas try the “If I lie here and stare at it long enough, it will open” strategy. Unfortunately, I haven’t seen this one work yet.
Sarah spent an amazing amount of time and effort developing the box and working out the kinks. During Sarah’s research, 9 Mara hyenas (out of 58 who tried) opened the box. On average, a hyena needed to work on the box three different times before they could open it. One smarty-pants, Snaggletooth, got so good at the task that he was able to open the box in 3 seconds; Kent, shown below, could do it in 5 seconds.
I'm now doing some work with the box here at Serena. While all this just the tip of the iceberg, it’s certainly a promising – and interesting – way to look at animals’ intelligence.
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5 comments:
I'm curious--which hyenas seemed to have a better chance of figuring it out? Did higher-ranking individuals do better than lower ones? Did there seem to be any parallels with age or sex?
In primates you often do see sex, age and rank differences in innovation. However, we have not seen those in the puzzle box work on the wild hyenas thus far. We have found no difference in success between low and high-ranking hyenas. We also have not seen any sex or age differences in success or participation in the wild hyenas. We are still wading through the data though and I will let you know if we find any interesting differences in other measurements. Great questions though!
Sarah
Do other animals get the box open? Or how do you restrict it to just hyenas? And are there any hyenas in a controlled environment where you could test this with other variables?
In Kenya we were focused exclusively on hyenas. We would only put the box out for a hyena when we had a good situation where other carnivores were not present. However, there was one time when a lioness was hiding in the grass and I did not see her until I had already put the box out. She did come over and try to get the meat out of the box a little bit, but she was unsuccessful and she lost interest pretty quickly.
It was fun trying to get my box back from her! We had to tie a tow rope around the box and drag it a safe distance away from the lioness before I could get out of the car to collect the box.
We have done an experiment with the puzzle box on captive hyenas as well. The captive hyena colony was a great opportunity for us to get a closer look at social learning.
Another graduate student in our lab, Greg Stricker, is testing a wide range of carnivores with the box. He has had some other species open it. So, it's not just hyenas who can figure it out.
i've been using my box to catch baby leopards...
but seriously the striped hyenas have no interest in these things
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