Smart cuttlefish have passed the marshmallow test


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Good things come to those who wait, especially the cuttlefish who hangs out with Alexandra Schnell, a comparative psychologist at the University of Cambridge in England. For the past decade, Schnell has been researching cephalopod behavior and cognition by giving them tests that are traditionally used to measure brain power in primates and other vertebrates. And the squishy creatures are doing remarkably well.

In fact, a new study suggests that cuttlefish may show self-control. When given the option, some people choose to forgo instant gratification if it means they can get a better reward in the future. In humans and other species, this ability, known as delayed maintenance, is believed to have been an important step on the evolutionary path toward making complex decisions.

Six subadult cuttlefish underwent the test, a version of the well-known marshmallow test first performed by Stanford researchers about 50 years ago. Each animal was presented with two cameras, one containing a readily available bite of raw shrimp, a regular snack in the eyes of a cuttlefish. The other was fattened with live grass shrimp, a more desirable option, but which became available only after a delay. If the cuttlefish waited for its preferred prey, the waiting time for the next round of the experiment was increased.

“The most surprising thing was that they were able to tolerate delays of 50 to 130 seconds,” says Schnell. “That is comparable to what we see in large-brained animals like chimpanzees, crows and parrots.”

Cuttlefish that waited longer for their favorite foods also performed better during learning tests, a link that has only been shown in humans and chimpanzees. In the future, Schnell and his team plan to expand the battery of tests to further explore that connection.

However, like humans, not all cuttlefish were star pupils. “You have the impatient,” says Schnell. “There was a cuttlefish that siphoned me repeatedly until I came over to feed it. They have a lot of character. “

Alexandra schnell

Alexandra Schnell, a comparative psychologist at the University of Cambridge in England, plans to further study the limits of cuttlefish cognitive prowess. Photo courtesy of the Grass Foundation

To make sure the animals were really weighing the options and using that information to inform their decision, the researchers introduced a different pairing. In this configuration, one chamber contained prawns and the other an unreachable shrimp.

“If their self-control is flexible and not only had I trained them to wait in any context, I would expect the cuttlefish to take the immediate payoff. [in this case]even if it’s his second preference, ”says Schnell. That’s exactly what happened. Also, this shows that the shrimp had not been removed from the menu.

“That’s something to try when looking for self-control with different quality foods,” says Schnell.

“If I give a kid an apple and say, ‘If you wait 15 minutes, you can have this candy bar,’ most of them would probably say, ‘No problem. I want the chocolate, ‘”says Schnell. The team needed to be sure that the cuttlefish would take their version of an apple if it was the only option.

There is another sign that may also indicate that the cuttlefish were deliberately waiting. During some tests, the cuttlefish seemed to push their bodies away from the immediate reward. “We see this in some other animals as a coping mechanism to try to resist temptation and hope for the best reward,” says Schnell. Parrots close their eyes; corvids and dogs wander away; chimpanzees try to distract themselves. Schnell doesn’t know yet if the cuttlefish is doing something similar, but the possibility is intriguing.

Jennifer Vonk, a cognitive and comparative psychologist at Oakland University in Michigan who was not involved in the study, is excited to see cuttlefish exposed to these kinds of tests. Testing a wider variety of species, he explains, can help us unravel the mystery of what drives cognitive prowess.

The lineage that gave rise to the cuttlefish and its relatives separated from the vertebrate lineage more than 550 million years ago. Their most recent common ancestor, a worm-like creature with a very simple nervous system, would not have had these abilities. This means that any cognitive traits shared by humans and cuttlefish evolved independently.

“Our brains are so structurally different,” says Schnell. “The mammalian brain is divided into two hemispheres and is made up of about five lobes. The cephalopod brain is donut-shaped. It has between 30 and 40 lobes, if it is a cuttlefish or an octopus, and it does not have these hemispheres. “

Donut-shaped brains aren’t the only thing that separates cuttlefish from large-brained vertebrates. One of the main hypotheses for the driving force behind advanced cognition is that it helped animals overcome the challenges of a complex social life. But the cuttlefish is not a cooperative social animal. They do not practice parental care and, at just two years old, their generations do not overlap. This means that cuttlefish do not form strong affiliations with relatives or partners. Some species even struggle to recognize members of the opposite sex. During mating, males will glue packets of sperm onto any individual they find.

“We don’t know if living in a social group is important for complex cognition unless we also show that those skills are lacking in less social species,” says Vonk. “There is still a lot of room to understand more.”

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