Humans, chimpanzees, parrots, and crows have evolved to exercise self-control, a trait associated with higher intelligence. Now researchers say squids – fat squid-like creatures with eight arms – also have the ability to delay gratification for better reward.
Researchers used a modified version of the Stanford marshmallow test, giving children the choice of either spotting an immediate reward (one marshmallow) or waiting for a delayed, but better reward (two marshmallows), on six squid in an aquarium setting .
The invertebrates were presented with rooms marked with different visual cues in the form of shapes. For example, one cue meant that the moment food was placed in that room, the door opened – while another meant that there would be a delay before the door opened if food was placed in that room. One of the cues was counterintuitive – although the food was placed in the room and the door opened, there was an extra layer of plastic that kept the squid from eating the reward.
When the squid were initially exposed to the chambers, they immediately attacked when they saw the food. Over time, they realized that each room had its own rules. In the end, the mollusks didn’t even bother to approach the “unreachable” room, finding that they could never access the food.
After the training was completed, the squid were tested in the presence of two chambers – in the “immediate” chamber they were shown their second preferred food, while in the “delay chamber” they were given their first preferred food.
In the control setting, these conditions were reflected, except that the delay chamber was the unreachable chamber. “We wanted to see if they were able to exercise self-control in a flexible way, depending on the context,” said lead author Dr. Alex Schnell, a behavioral ecologist from the University of Cambridge.
“They could see their favorite foods in the unreachable room, but they could never get there – so they had to make a decision whether to try or just take the immediate option.”
Overall, the squid slowed gratification when it led to a higher quality prey item and was able to sustain delays for periods of up to 50 seconds to 130 seconds, the authors wrote in the journal Proceedings of the Royal Society B .
Previous research had suggested that some primates and birds showed this advanced level of self-control because they were social species that maintained multiple relationships and used tools, Schnell said.
These species cannot forage or hunt at any given time, so they could build tools or wait for their mate to eat, she noted. “But that does not apply to squid … they are not social and do not use tools.”
Instead, squid self-control could have evolved to maximize efficiency, she speculated. “It’s a juicy meal… so they spend very long periods camouflaged, and remain virtually immobile so they can avoid being spotted by predators. And this motionless behavior is broken when squid forage. “