Decision strategies appear similar across species and development, but differences emerge in the speed-accuracy relationship
By combining Conditional Accuracy Functions and Drift Diffusion Modeling, this study reveals that while humans and macaques share an evolutionarily conserved decision-making framework involving collapsing boundaries, children exhibit distinct fast-error patterns driven by unstable initial decision states likely due to immature frontostriatal networks.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of a preprint that has not been peer-reviewed. It is not medical advice. Do not make health decisions based on this content. Read full disclaimer
Every time we make a choice, from picking a route to work to deciding what to eat, our brains are balancing two competing demands: how fast we act and how right we are. Usually, these two goals pull in opposite directions. If we rush, we are more likely to make a mistake; if we take our time to think, we are more likely to get it right. Scientists call this the speed-accuracy trade-off. For decades, researchers have studied this balance to understand how the mind works, often looking at how quickly people respond to see if their errors happen when they are rushing or when they are hesitating. This simple relationship between speed and mistakes can reveal a lot about the hidden strategies our brains use to solve problems. It can even show how these strategies change as we grow up or differ between humans and other animals.
A team of researchers at Sapienza University of Rome, along with colleagues at the Bambino Gesù Children's Hospital, decided to look closely at this balance across different ages and species. They wanted to know if the way children, adults, and monkeys make decisions is fundamentally the same, or if the path to a decision changes as the brain matures. To find out, they asked sixty-two children, eighty-three adults, and two rhesus macaques to play a game of logical ranking. The game involved learning the order of six abstract images, like knowing that image A is "greater" than B, B is greater than C, and so on. Once they learned the order of neighbors, the participants were tested on pairs they had never seen together before, forcing them to use logic to figure out which item was higher in the ranking. This type of task is known to get harder when the items are close together in the ranking and easier when they are far apart, a pattern that all the groups in the study successfully learned.
When the researchers looked at the results, they found that while everyone learned the rules, the way they made mistakes told a very different story. The adults and the monkeys behaved in a remarkably similar way. For them, mistakes were most likely to occur when they took the longest to respond, suggesting that as time passed, they might have become uncertain or lost focus. However, the children showed a distinct pattern. A significant portion of the children made a specific kind of mistake: they guessed too quickly. About forty-two percent of the children in the study met a specific criterion for making these "fast errors," giving answers so fast that they were essentially random, showing no real understanding of the logic at all. These "fast errors" were not found in the adult group or in the monkeys, who did not exhibit this specific pattern of rushing into incorrect answers. The children who made these fast guesses were not just slower or less smart; they were starting their decision process from a different place, often committing to an answer before they had gathered enough information.
To understand what was happening inside the brain during these choices, the researchers used a mathematical model that simulates how evidence builds up over time to reach a decision. Imagine a bucket filling with water; the water represents the evidence for a choice, and the decision is made when the water hits a certain level. The researchers found that for adults and monkeys, the water filled up steadily, and the level needed to make a decision actually dropped slightly over time, creating a sense of urgency. This explained why they made mistakes when they waited too long. But for the children who made fast errors, this model only worked if the researchers added a new element: the starting point of the water level was unstable. Sometimes, the bucket started nearly empty, and sometimes it started almost full, purely by chance. This instability meant that for some children, the decision process began already tipped toward a wrong answer, leading to a quick, incorrect guess before any real thinking could happen.
The study suggests that while the basic machinery for making logical inferences is shared across species and exists early in human development, the ability to stabilize the very beginning of a decision is still under construction in children. The brain networks responsible for stopping impulsive reactions and holding a steady focus are not fully mature until early adulthood. The children who made fast errors were not failing because they lacked the logic; they were failing because their internal starting point was shaky, making them prone to acting on impulse before they were ready. This research offers a clear window into how decision-making evolves, showing that the journey from childhood to adulthood involves not just learning more facts, but learning how to steady the mind before it acts.
Drowning in papers in your field?
Get daily digests of the most novel papers matching your research keywords — with technical summaries, in your language.