Raccoons will solve puzzles just for fun
Raccoons might want to break into your trash can even without delicious leftovers inside
For a raccoon, breaking into your garbage might be just as satisfying as cracking a crossword
puzzle or a Sudoku is for you, according to new research.
These meddlesome “trash pandas” have dexterous paws and considerable brain power that have
helped them thrive in a human-dominated world—even showing early signs of domestication—
constantly thwarting attempts to keep them from ransacking waste bins for tasty morsels.
“Raccoons have very dense brains, and that likely explains their heightened ability to
solve problems and to be behaviorally flexible,” says Lauren Stanton, a cognitive ecologist
at the University of California, Berkeley.
But new research published in Animal Behaviour suggests raccoons will try to solve problems
even when they don’t expect a food reward for the work. The scientists describe the behavior
as foraging for information, rather than food, in preparation for facing future challenges.
The study relied on what researchers call a multiaccess puzzle box, a clear plastic box that
has multiple doors and windows—sometimes equipped with locks and latches of various levels
of difficulty—that an animal must opento get at a treat inside. (The scientists let the
captive raccoons they were working with pick between marshmallows, sardines and dates dipped
in sardine juice as their reward; marshmallows were far and away the most popular choice.)
Usually, scientists give the puzzle box, see what solution the animal finds and then give them
the box again, this time with the first solution disabled. They want to see if the critter will
find a new way to access their treat. In the new study, the researchers turned this formula on
its head and gave the raccoons the unmodified (but refilled) box for multiple trials to see
what the raccoons did.
“Going into it, I was expecting they’ll open one solution, they’ll get the marshmallow out,
and then they’ll leave the box alone, and then, when I give it back to them in their next trial
with another marshmallow, maybe they’ll open another solution,” says study co-author Hannah
Griebling, a Ph.D. candidate in cognitive ecology at the University of British Columbia.
But the raccoons went above and beyond, nosing into the alternative solutions practically as
soon as they’d nommed their marshmallow, not waiting for a refill. The continued investigations
became less common as the solutions to the puzzle box became more complex, but they never fully
stopped.
Griebling and her colleagues call that continuing work on the puzzle boxes “information foraging”
—essentially positing that the raccoons are taking advantage of the opportunity to investigate
the additional entry mechanisms in case they run into the same situation in the future.
Of course, “we can’t know what they’re thinking; we can only measure their behavior,”
Griebling says. But the finding is striking proof that something besides their taste for
marshmallows is driving the animals’ continued examination—and that it could be not too
different from the kind of curiosity and satisfaction humans experience when problem-solving
masquerades as puzzles. “We think there could be some sort of intrinsic motivation for that
behavior,” Griebling says.
Both Griebling and Stanton note that it would be valuable to repeat the work with wild raccoons,
which may be more attuned to the risks of wasting time fiddling around with a lock they can’t
figure out how to open. (Stanton has worked with the researchers before but was not involved in
this experiment.)
And plenty of humans would appreciate a better understanding of how to convince trash pandas a
puzzle isn’t worth investigating any more. If you’re one of them, Griebling’s advice is simple:
“Really ensuring that they can’t get into something, instead of potentially giving them more
challenges to solve, is probably important.”