Raccoons have long been credited with outwitting latches, and a study has tested that reputation.
asserted
study → credit → reputation
University of British Columbia researchers Hannah Griebling and Dr Sarah Benson-Amram gave captive raccoons a custom puzzle box with nine entry points, grouped as easy, medium and hard.
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Griebling → give → points
Each 20-minute trial held a single marshmallow; the raccoons often kept opening new mechanisms after eating it.
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raccoons → hold → it
Sixteen adult raccoons were tested in Colorado, and fourteen completed all three difficulty levels.
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fourteen → test → levels
The authors call the behaviour information foraging, and the paper reports that all but one raccoon solved multiple solutions within single trials.
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raccoon → call → trials
How did scientists test raccoons with a nine-way puzzle
According to the University of British Columbia news release, the researchers used a custom multi-access puzzle box with mechanisms such as latches, sliding doors and knobs.
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researchers → test → latches
The box had nine entry points, grouped as easy, medium and hard.
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box → have → points
The paper states that the box was a Plexiglas cube measuring 25.4 centimetres on each side, with removable panels.
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box → state → panels
One panel was plain Plexiglas, and the other three held solutions that gave access to the food in the centre, so each raccoon faced three solutions at a time.
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raccoon → hold → time
The easy ones were a door, a slide latch and a pull-down window.
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ones → pull → ?
The medium ones were a hook-and-eye latch, a hasp latch and a push-up window.
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ones → push → ?
The hard ones were a draw-catch latch, a turn knob and an unlocked padlock placed in the hasp.
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ones → draw → hasp
According to the paper, sixteen adult raccoons were tested at the United States Department of Agriculture's National Wildlife Research Centre in Fort Collins, Colorado.
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raccoons → accord → Collins
Eight were captive-reared males, six were captive-reared females, and two were wild-caught males.
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two → rear → ?
Fourteen completed all three difficulty levels.
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Fourteen → complete → levels
Why did raccoons keep solving the puzzle after eating the marshmallow
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raccoons → keep → marshmallow
According to the study published in ScienceDirect, titled ‘
Raccoons optimally forage for information: exploration–exploitation trade-offs in innovation’, each raccoon had five trials a night for 10 nights, giving 50 trials in total.
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raccoon → accord → total
Trials lasted 15 to 20 minutes, and most ran for the full 20.
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most → last → 20
The raccoons were not deprived of food, although their second daily ration was held back until testing finished each night.
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testing → deprive → food
Before the puzzle trials, a food preference test showed that the raccoons were more likely to choose a marshmallow than a dried prune dipped in sardine juice or a sardine.
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raccoons → show → juice
Each raccoon met the easy solutions first.
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raccoon → meet → solutions
It moved on to the next level only after opening one solution 15 cumulative times.
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It → move → solution
The box held a single marshmallow in each 20-minute trial, yet raccoons often continued opening new mechanisms after eating it.
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raccoons → hold → it
"They kept problem-solving even when there was no marshmallow at the end," Griebling said.
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Griebling → keep → end
The paper reports that all but one raccoon solved multiple solutions within single trials at all three difficulty levels.
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raccoon → report → levels
The raccoons could see and feel with their forepaws that no further food was inside the box.
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food → see → box
How did raccoons change their puzzle-solving strategies
The raccoons took longer to solve their first hard solution than their first easy or medium one.
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raccoons → change → one
The mean number of solutions solved per trial was 1.79 for easy, 1.63 for medium and 1.44 for hard.
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number → solve → hard
The paper also scored how varied the raccoons' solving order was, on a scale from 0 to 1.
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order → score → 1
The authors say this shows the raccoons explored more on easier problems and relied on known solutions more on harder ones.
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raccoons → say → ones
UBC states that raccoons tried multiple openings and varied their order when solutions were easy.
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solutions → state → order
As difficulty rose, they favoured a dependable solution, but they still explored several solutions at the hardest level.
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they → rise → level
Griebling compared the pattern to ordering at a restaurant, choosing a favourite dish or trying something new.
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Griebling → compare → something
In her words, as reported by UBC, raccoons explore when the cost is low and play it safe when the stakes are higher.
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stakes → report → it
The paper adds that the more time raccoons spent exploring the box, the more solutions they solved.
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they → add → solutions
That exploration also slowed how quickly they opened the first solution and reached the food.
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they → slow → food
The authors report that this effect diminished as trials continued.
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trials → report → ?
PC: Canva
How do raccoons’ problem-solving skills help them thrive in cities
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them → help → cities
The findings help explain why raccoons thrive in urban centres such as Vancouver.
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raccoons → help → Vancouver
The release says their forepaws are rich in sensory nerves for foraging in streams, which suits them to handling latches and handles as humans do.
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humans → say → latches
…and 7 more, not listed.
The Aporia
