Alex Schnell
- Cuttlefish can show the same amount of self-control as bigger-brained animals, a test found.
- The fish resisted taking food immediately to get a better reward later.
- Similar tests are used on humans, usually children, to test cognitive development.
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Cuttlefish can be as good at controlling their urges as animals like chimpanzees, crows and parrots, researchers have said.
In a new study published Wednesday, scientists put six cuttlefish in conditions that would test whether they could delay gratification for a bigger reward.
The test was an underwater variant of what is commonly known as the marshmallow test, where participants can get a food reward straightaway, or hold out for something better like a marshmallow.
The cuttlefish were presented either with a piece of king shrimp or a more appealing live grass shrimp.
If they decided not to immediately take the piece of dead shrimp, the more appealing live shrimp would be offered after a delay.
This video was filmed by Dr. Alexandra Schnell, lead scientists on the study and a researcher of the University of Cambridge's Department of Psychology. It shows how her cuttlefish prefer the live shrimp, here on the left, over the king prawn, on the right:
—Marianne Guenot (@Marianne_Guenot) March 3, 2021
Schnell found that even the most impatient cuttlefish could wait 50 seconds before the live grass shrimp was released.
The cuttlefish with the most self control "could wait for over two minutes for a better snack", Schnell said in a press release.
This is comparable to what is seen in animals with larger brains such as chimpanzees, crows, and parrots.
This is quite "sophisticated behaviour", Prof. Nicola Clayton of Cambridge University, one of the scientists on the paper said in a press release.
"Self-control requires an understanding that 'less is sometimes more'- that avoiding temptation now might lead to a better future outcome", she said.
This original version of this is the Stanford marshmallow test, a experiment where children are told they can decide to either get a small reward immediately, such as a pretzel stick, or wait 15 minutes for a bigger reward, such as a marshmallow.
The scientists also tested whether smarter cuttlefish were better at waiting.
"We found that cuttlefish with better learning performance - an indicator of intelligence - also showed better self-control", Shnell said.
This is similar to what has been shown in humans and chimpanzees, but it is the first time it has been shown in a non-primate species, Schnell said.
The intelligence of cuttlefish is often studied by scientists. Their highly complex brains can control a set of pixels on their skin to change color and blend into their surroundings.
See how another type of cuttlefish can change skin colours in this video:
A study published in 2016 showed that cuttlefish has a sense of numbers, as they can tell the difference between different numbers of shrimp.