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The cuttlefish can pass the “marshmallow test” – the famous psychological test of self-control.
In this case, cephalopods were willing to forgo meals when they knew the wait meant they would be rewarded with more delicious treats, according to a new study. This makes them the first known invertebrates to show their ability to control themselves.
Common cuttlefish (Sepia officinalis) – parents of squid and octopus – are devious hunters and awesome camouflers, with the ability to quickly vanish in any environment. They are also terribly intelligent; previous studies have shown that they have good memories, can learn the value of different types of prey, and can use past experience to help them predict where to find food.
But prior to this study, it wasn’t clear if these creatures could delay satisfaction as well.
Related: Cuttlefish cuties: photos of cephalopods changing color
“Self-control is considered the cornerstone of intelligence, as it is an important prerequisite for complex decision-making and planning for the future,” said lead author Alex Schnell, researcher associated with the Department of Psychology at the University of Cambridge. . Not all animals share this trait, and it was previously thought that those that do, such as the great apes, corvids and parrots, have a long and social life.
To see if a cephalopod should join the ranks, Schnell and his team adapted the famous “marshmallow test” to appeal to the cuttlefish. In the 1960s, Walter Mischel conducted an experiment at Stanford University to test children’s self-control when presented with a favorite treat like a marshmallow (or other treats like cookies and pretzels) and two options: either eat a marshmallow now or wait 15 to 20 minutes and be rewarded with two marshmallows.
In the current study, Schnell’s team replaced marshmallows with seafood snacks, after determining what six 9-month-old cuttlefish (not yet fully grown) preferred to eat. It turned out that everyone preferred the live grass shrimp, followed by the king shrimp, with the Asian shore crab coming last of the three.
They then set up a two-chamber device with see-through sliding drawers. Behind one drawer, they placed a favorite meal (like live grass shrimp) and behind the other, they placed a less preferred meal (like Asian shore crab). The doors bore symbols indicating whether it would open with a delay (a triangle) or open immediately (a circle), which the cuttlefish learned to recognize.
The drawer with the least favorite meal always opened for the cuttlefish immediately, but the other drawer opened after a while. In the control condition, the door with the favorite snack did not open at all (a square). When the cuttlefish approached one room, the researchers immediately removed the snack in the other.
A little mystery
The cuttlefish indeed chose to delay the gratuity to mark a more delicious meal if it knew that the door would open after a delay; they were able to delay eating their snack for 50 to 130 seconds. During this time, they usually sat at the bottom of the tank to watch the two awards, Schnell told Live Science in an email.
Sometimes they even shied away from the immediate option (less preferred but currently available) “as if to distract themselves from the temptation of immediate reward,” she said. This same distraction technique has been previously observed in humans, chimpanzees, jays, parrots and dogs, she said.
“Why the cuttlefish has evolved in its ability to control itself is a bit of a mystery,” said Schnell. “This finding is an extreme example of convergent evolution because cuttlefish have significantly different evolutionary histories than most studied monkeys, corvids and parrots, and yet they share the same cognitive characteristic.” (Convergent evolution occurs when different species develop similar traits independently of each other.)
“Cuttlefish can tolerate delays in obtaining better quality food comparable to that of some large-brained vertebrates,” the authors wrote in the study. These include great apes, parrots, and corvids. But the benefits of self-control for these social and long-lasting animals “are obvious,” Schnell said.
If these animals resist the temptation now, they may perform better in the future and live longer. For example, these animals may wait for others to eat to strengthen social bonds or forgo hunting and foraging to give themselves time to craft tools to optimize hunting and foraging in the country. future, she said.
The benefits for cuttlefish are less obvious. “Cuttlefish don’t live long, aren’t social, and don’t craft or craft tools,” Schnell said.
Researchers hypothesize that the cuttlefish developed self-control as a by-product of an independent trait: camouflage. To avoid detection by predators, cuttlefish must spend long periods of their day in hiding, taking only brief breaks to feed. “Thus, self-control may have evolved to optimize their foraging behavior and reduce their exposure to predators,” she added.
The researchers also tested whether the degree of self-control in the cuttlefish was related to higher intelligence or, in this case, the cuttlefish’s ability to learn. To do this, they trained the cuttlefish to associate the reward with various stimuli; Cuttlefish who exercised greater self-control (waited longer for their food) had a better ability to learn, according to the results.
To link self-control with intelligence, researchers need to study how cuttlefish behave in other cognitive tests such as spatial memory and object permanence, which means understanding that a object continues to exist whether you can see it or not, Schnell said.
The results were published Tuesday March 2 in the journal Proceedings of the Royal Society B.
Originally posted on Live Science.
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