UChicago researchers have found that cuttlefish can delay gratification by resisting readily available snacks in exchange for better ones later on. The research, published on March 3 in Proceedings of the Royal Society B, marks the first time a link between self-control and intelligence has been found in an animal other than humans and chimpanzees.
To test self-control, researchers repeatedly presented the cuttlefish with a small meal, followed by a second, larger meal. Over time, the cuttlefish began abstaining from the first meal and opting instead for the second meal, exhibiting a phenomenon known as delayed gratification. To test learning performance, a reversal-learning task was used, in which cuttlefish were required to learn to associate a reward with stimuli and then learn to associate the reward with an alternative stimulus.
“We used an adapted version of the Stanford marshmallow test, where children were given a choice of taking an immediate reward [of one marshmallow] or waiting to earn a delayed but better reward [of two marshmallows],” lead author Alexandra Schnell said. “Cuttlefish in the present study were all able to wait for the better reward and tolerated delays for up to 50–130 seconds, which is comparable to what we see in large-brained vertebrates such as chimpanzees, crows, and parrots.”
Finding this link between self-control and intelligence in a species outside of the primate lineage is an example of convergent evolution, in which different evolutionary histories have led to the same cognitive feature. In humans, studies have linked self-control with cognitive performance, in that individuals who delay gratification for longer achieve higher scores in a range of academic tasks. Researchers have found the same association among other highly social species, particularly chimpanzees.
Cuttlefish, however, are not social species, and therefore their capacity to evolve for self-control is more surprising. Delayed gratification in humans is thought to benefit the species as a whole—for instance, waiting for a partner in order to eat dinner together is considered to strengthen social bonds. It may also function in other social animals who need to wait for prey while hunting. As cuttlefish are not social species and do not hunt for prey, the authors of the study suggested that delayed gratification may be a byproduct of the cuttlefish’s need to camouflage to survive.
“Cuttlefish spend most of their time camouflaging, sitting and waiting, punctuated by brief periods of foraging,” Schnell said. “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.”
