Cuttlefish reveal link between self-control, intelligence

Cuttlefish are able use self-control to delay gratification, ignoring an immediate reward in hopes of a bigger reward later. Photo by Alexandra Schnell
Cuttlefish are able use self-control to delay gratification, ignoring an immediate reward in hopes of a bigger reward later. Photo by Alexandra Schnell

March 2 (UPI) -- According to a new study, cuttlefish can pass the Stanford marshmallow test, delaying the gratification of an immediate reward for a better reward later.

In the 1970s, Stanford psychologist Walter Mischel used the marshmallow experiment to test the self-control of young children.


The experiment proved the ability to delay gratification was associated with a range of better life outcomes: higher SAT scores, greater educational attainment and lower body mass indexes, to name a few.

The latest research, published Tuesday in the journal Proceedings of the Royal Society B, showed cuttlefish with greater self-control score better on intelligence tests.

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"We used an adapted version of the Stanford marshmallow test, where children were given a choice of taking an immediate reward, one marshmallow, or waiting to earn a delayed but better reward, two marshmallows," lead author Alexandra Schnell said in a press release.

"Cuttlefish in the present study were all able to wait for the better reward and tolerated delays for up to 50 to 130 seconds, which is comparable to what we see in large-brained vertebrates such as chimpanzees, crows and parrots," said Schnell, a behavioral ecologist and research fellow at the University of Cambridge.


In a followup test, researchers trained cuttlefish, marine mollusks related to squid and octopi, to associate a visual cue with a food reward.

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Later, researchers reversed the associations, forcing the cuttlefish to adapt. The cuttlefish that delayed gratification for the longest were the quickest to learn and relearn the visual cue-food associations.

Some researchers hypothesize that humans evolved the ability to delay gratification for social purposes. Waiting for a partner to eat first, for example, can reinforce social bonds and encourage further cooperation.

Other scientists suggests delayed gratification is essential for tool-using animals -- tools don't do any good if hunters chase after prey before the tool has been constructed.

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Neither of these theories can explain why cuttlefish practice delayed gratification. They are not social animals, and they don't use tools.

Cuttlefish are, however, patient animals.

"Cuttlefish spend most of their time camouflaging, sitting and waiting, punctuated by brief periods of foraging," Schnell said. "They break camouflage when they forage, so they are exposed to every predator in the ocean that wants to eat them. We speculate that delayed gratification may have evolved as a byproduct of this, so the cuttlefish can optimize foraging by waiting to choose better quality food."


It's not the first time scientists have shown cuttlefish manipulate their present behavior in anticipation of future events.

Last year, researchers showed that when cuttlefish know their favorite food, shrimp, is on the dinner menu, they make sure not to fill up on crabs during the day.

The authors of the latest study suggest the cuttlefish's impressive self-control is evidence of convergent evolution, the independent development of a specific trait among two or more animal lineages.

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