A Cephalopod Passed a Human Children's Cognitive Test

 

Sepia officinalis is a medicinal plant. (Getty Images/Schafer & Hill/The Picture Bank)

A recent test of cephalopod intelligence has highlighted the importance of humans not underestimating animal intelligence.

Cuttlefish have been put through a new iteration of the marshmallow test, and the findings seem to show that their peculiar little brains have more going on than we previously believed.

Cuttlefish's ability to learn and adapt may have evolved to give them an advantage in the cutthroat eat-or-be-eaten aquatic environment in which they live, according to the researchers.

The marshmallow test, also known as the Stanford marshmallow experiment, is a simple one. A marshmallow is put in a room with a boy. They are told that if they can go 15 minutes without eating the marshmallow, they will be given a second marshmallow and allowed to eat both.

This ability to delay gratification reflects cognitive skills such as future planning, and it was originally conducted to learn more about how human cognition evolves, specifically when a human is wise enough to delay gratification if it means a better outcome later.

It can be adapted for animals because it is so plain. You can't tell an animal that if they wait, they'll get a better reward, but you can teach them that if they don't eat the food in front of them right away, better food will come.

Dogs, like certain primates, may postpone gratification, although infrequently. The marshmallow test has been passed by corvids as well.

Cuttlefish have passed a variant of the marshmallow test last year. Scientists discovered that common cuttlefish (Sepia officinalis) will stop consuming crab meat in the morning if they know that dinner will be something they like - shrimp.

However, as a team of researchers led by behavioral ecologist Alexandra Schnell of the University of Cambridge point out in a new paper, it's difficult to tell if this shift in foraging behavior in response to prey availability was also governed by self-control in this case.

As a result, they invented a new test for six common cuttlefish. The cuttlefish were housed in a special tank with two enclosed chambers with transparent doors that enabled them to see inside. Snacks were available in the chambers, including a less-appealing raw king prawn in one and a slightly more appealing live grass shrimp in the other.

The cuttlefish had been taught to identify symbols on the doors as well. A circle suggested that the door would open instantly. The door would open after a time interval of 10 to 130 seconds if the form was a triangle. A square, which was only used in the control situation, meant that the door would remain closed indefinitely.

The prawn was put behind the open door in the test condition, while the live shrimp was only accessible after a pause. The shrimp was automatically removed if the cuttlefish went after the prawn.

Meanwhile, behind the square-symbol door that wouldn't open in the control group, the shrimp remained unavailable.

The researchers discovered that all of the cuttlefish in the test condition wanted to wait for their desired food (live shrimp), while none of the cuttlefish in the control group did.

Cuttlefish in this study were all able to wait for the better reward and tolerated delays of up to 50-130 seconds, which is similar to what we see in large-brained vertebrates like chimps, crows, and parrots, according to Schnell.

The experiment also included a measure of how well the six cuttlefish could understand. A grey square and a white square were shown to them as visual clues. If they reached one, the other would be removed from the tank, and they would be rewarded with a snack if they made the "right" option.

When the researchers had learned to equate a square with a reward, they reversed the cues, making the other square the reward cue. Surprisingly, the cuttlefish that learned to adapt the fastest were also the cuttlefish that could wait longer for the shrimp reward.

Cuttlefish seem to be capable of self-control, although the reason for this is unclear. Delay gratification has been related to factors like tool usage (because it involves preparation ahead), food caching (for obvious reasons), and social competence in species like parrots, primates, and corvids (because prosocial behavior - such as making sure everyone has food - benefits social species).

Cuttlefish do not use tools or cache food, and they are not very social, as far as we know. Cuttlefish's ability to postpone gratification may have something to do with how they forage for food, according to the researchers.

Cuttlefish spend the majority of their time camouflaging, sitting, and waiting, with occasional bursts of foraging thrown in for good measure, according to Schnell.

When they forage, they lose their camouflage, exposing themselves to any predator in the ocean trying to eat them. We assume that delayed gratification evolved as a result of this, allowing the cuttlefish to maximize foraging by waiting to pick higher-quality food.

It's an intriguing example of how very different lifestyles in very different species can result in behaviors and cognitive abilities that are remarkably similar. The team suggests that future studies should focus on determining whether cuttlefish are capable of preparing for the future.

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