The ability to delay gratification is a hallmark of advanced cognitive function, observed across a variety of species from humans to chimpanzees. This fundamental skill, the choice between an immediate, smaller reward and a delayed, larger one, significantly influences daily decisions and is often associated with enhanced problem-solving abilities and long-term success. While this link has been extensively studied in mammals and birds, evidence of such self-control in invertebrates has been less common.
A groundbreaking new study featuring cuttlefish, soft-bodied marine predators, challenges this notion. It reveals that these fascinating creatures possess the patience and cognitive capacity to perform comparably to some of the most intelligent vertebrates in a test inspired by the famous "marshmallow test." The research was led by Alexandra Schnell of the University of Cambridge, in collaboration with Marine Biological Laboratory senior scientist Roger Hanlon and their team.
The power of patience
Self-control can be understood as a mental mechanism that allows an individual to forgo an instant reward for a more substantial one in the future. In humans, strong self-control is linked to positive outcomes such as higher academic achievement, greater financial stability, and healthier lifestyle choices.
Among animals, species like apes, parrots, and crows frequently exhibit this patience, whereas others, including monkeys, rats, and pigeons, rarely do. Biologists propose that these variations are tied to each species' unique survival strategies. Factors such as lifespan, growth rate, and food availability all play a role in shaping a creature's capacity for delayed gratification. For instance, long-lived animals can afford to wait, and social species might delay consumption until group members arrive. Predators that stalk elusive prey, from ravens to reef fish, also benefit from biding their time.
The underwater marshmallow test
The original marshmallow test famously presented preschoolers with a choice: one marshmallow immediately, or two if they could wait for 15 minutes. To adapt this experiment for an aquatic environment, the research team offered hungry cuttlefish a piece of ordinary shrimp. Simultaneously, they placed a more desirable live grass shrimp behind a clear barrier. Sliding doors allowed each cuttlefish to view both treats, controlling when each became accessible.
The results were compelling. While some cuttlefish immediately consumed the plain shrimp, others demonstrated remarkable restraint, hovering and observing for over two minutes before choosing the preferred live grass shrimp when it became available. The cuttlefish participating in the study were able to tolerate delays ranging from 50 to 130 seconds to secure the better reward. This level of delayed gratification is comparable to what has been observed in large-brained vertebrates such as chimpanzees, crows, and parrots.
"We utilized an adapted version of the Stanford marshmallow test, where children were given a choice of taking an immediate reward (1 marshmallow) or waiting to earn a delayed but better reward (2 marshmallows)," explained Schnell.
Why cuttlefish exhibit delayed gratification
Cuttlefish spend the majority of their time camouflaging, patiently waiting, with brief intervals of foraging. "They break camouflage when they forage, so they are exposed to every predator in the ocean that wants to eat them," Schnell noted. "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." This explanation aligns perfectly with their daily routines, as a cuttlefish can seamlessly blend its skin with its surroundings in less than a second, then remain motionless for hours.
Discovering widespread intelligence
While octopuses and squids have already gained recognition for their problem-solving abilities, such as navigating mazes and using coconut shells as shelters, cuttlefish now join their ranks. Their performance in this study provides further evidence that sophisticated behaviors are not solely dependent on large brains, highlighting the diverse pathways to intelligence found throughout the animal kingdom.
Picture: Cuttlefish attentively filling out an IQ test in a classroom (Gemini)
