Researchers in Japan built a hide-and-seek video game for monkeys, offered no food for playing it, and watched what happened. Some Japanese macaques kept tapping for nearly 100 rounds anyway. Given a choice, the animals shifted toward the button that made a cartoon puppet pop up in places that were somewhat unpredictable, rather than nearly identical every time or completely random.
The study, published online April 18 in iScience by scientists at Kyoto University’s Institute for the Evolutionary Origins of Human Behavior, adds evidence that monkeys share a curiosity pattern seen in people: a pull toward things that are neither too simple nor too chaotic.
The Noise Was About Location, Not Sound
The experiment is sometimes described as a test of how monkeys respond to different noise levels. Here, noise has a statistical meaning. Each button on the touchscreen made a puppet appear at a location set by its own rule, according to a Japanese-language Kyoto University release. A low-noise button made the puppet appear in roughly the same place each time. An intermediate-noise button kept some predictability while adding moderate uncertainty. A high-noise button made the location random.
Eleven Japanese macaques living at the institute took part. In the first experiment, they chose between intermediate-noise and low-noise buttons. In the second, they chose between intermediate and high noise.
To separate real interest from simple habits, the team compared those sessions with a condition in which the differences between buttons could not be perceived because the puppet did not appear.
A Modest but Consistent Preference
When the puppet’s movements were visible, the macaques shifted their choices toward the intermediate-noise button by 9.6% against low noise and by 13.5% against high noise, according to the study abstract. They also chose that button again more quickly, which the researchers see as a sign of stronger motivation.
Those shifts are not dramatic, and the study involved a small group of captive animals. Still, the direction was the same in both experiments.
First author Sakumi Iki, who previously studied play behavior in wild monkeys, said he had doubts that the animals would engage without food, since monkeys in cognitive tasks are usually rewarded. Instead, some “worked on this game for nearly 100 trials even without any reward,” Iki said in a Kyoto University release.
Why Just Unpredictable Enough Matters
The pattern fits what scientists call the Goldilocks principle of curiosity. Human infants pay the most attention to visual sequences that are neither too simple nor too complex, as a 2012 study of infant attention showed. A 2022 study found that macaques preferentially attend to intermediately surprising information.
What is new here is action. Most earlier work measured how long animals looked at something, and longer looking does not always mean an animal will act to see it again. In this game, the macaques used their own taps to recreate moderately uncertain events. The researchers suggest the tendency may help animals focus on what they can learn the most from, rather than on things that are trivial or impossible to predict.
From Monkey Enrichment to Human Learning
The team hopes reward-free games could become enrichment tools that improve living conditions for animals in laboratories and zoos, and possibly for pets such as cats and dogs. Next, the researchers want to test whether the macaques actually experience positive emotions while they play, and to design games that draw out curiosity even more strongly.
The work has clear limits. The study tested one species, one kind of unpredictability, which was where a puppet appeared, and a small group of animals in a lab setting. Whether the same pattern holds for sounds, other kinds of complexity, or other species remains to be tested.
Still, the findings echo something familiar to teachers and game designers. People tend to stay engaged when a challenge is hard enough to be interesting but not so hard that it feels hopeless. The macaque study suggests that sweet spot may be a trait humans share with other primates.
Key Questions Answered
What did the macaques do in the study?
Eleven Japanese macaques played a reward-free touchscreen game, choosing between buttons that made a puppet appear in more or less predictable locations.
Was the study about loud and quiet sounds?
No. “Noise” referred to how much the puppet’s location varied from one appearance to the next.
Which option did the monkeys prefer?
They shifted toward the intermediate option, where the puppet’s position was somewhat unpredictable, over both the highly predictable and the fully random options.
How strong was the effect?
Modest. Choices shifted by 9.6% and 13.5% compared with a condition in which the differences could not be seen.
Why does this matter beyond monkeys?
It supports the idea that a preference for moderate uncertainty, seen in human infants, is shared with other primates and could guide better enrichment and learning designs.
Published by Medicaldaily.com