Higher cognitive ability in adults typically predicts accurate gut instincts, but this mental shortcut takes time to develop. A new study involving middle and high school students reveals that young people rely heavily on slower, deliberate thinking to solve logical puzzles before their correct intuitions fully mature. The research was recently published in the journal Thinking & Reasoning.
Psychologists often divide human thought into two distinct categories based on speed and effort. The first type of thinking is fast, automatic, and requires very little mental energy. The second type is slow, deliberate, and demands sustained attention to detail.
For decades, researchers assumed that successfully solving a math or logic puzzle always required the second, slower type of thought. In this traditional view, our fast assumptions are often biased or flawed. To reach a mathematically sound conclusion, a person has to actively block their immediate instincts and spend time calculating the right answer.
Recent studies on adult reasoning have challenged this assumption. Scientists have found that many adults can produce correct, logical answers almost instantly. They do not need to pause and engage in slow reflection to solve basic probability questions.
This phenomenon is often linked to general intelligence. Adults who score high on cognitive ability tests tend to have accurate initial instincts. This alignment of intelligence and immediate accuracy has led researchers to call them “smart intuitors.”
A team of psychology researchers wanted to know exactly when this capacity for accurate intuition develops. Lead author Laura Charbit and her colleagues at the Université Paris Cité in France designed an experiment to test reasoning skills across adolescence. They wanted to see if middle and high school students might already show the mature profile found in adults.
The research team recruited more than 300 students from French secondary schools. Roughly half the participants were seventh graders, averaging around 12 years of age. The other half were twelfth graders nearing the end of their secondary education, averaging around 17 years old.
To measure how the students thought, the researchers gave them a series of probability puzzles. The puzzles were designed to create a conflict between a statistical fact and a tempting stereotype. For example, participants read about a study containing 995 accountants and five clowns.
The students were then asked to guess the profession of a randomly selected person from the study, labeled Person L. The prompt described Person L using a single word: funny. Based on the stereotype of a clown, the fast and tempting answer is to assume Person L is a clown.
Mathematically, however, the odds heavily favor a different answer. Because there are 199 times more accountants than clowns in the group, the randomly selected person is overwhelmingly more likely to be an accountant, even if they happen to have a good sense of humor. Arriving at this correct answer requires paying attention to the baseline statistics rather than the descriptive personality trait.
To separate fast instincts from slow deliberation, the researchers used a specialized testing format. For the first part of the trial, students had to give an answer in three seconds or less. To make it even harder to think deeply, the students had to memorize a grid of symbols before reading the puzzle.
This memory task occupied their active attention, forcing them to rely on pure instinct for their initial response. After giving their fast answer and recalling the grid, the students saw the puzzle a second time. During this second phase, they had unlimited time to think and could change their original answer if they desired.
The researchers also included control puzzles where both the personality description and the statistics pointed toward the exact same answer. Both age groups performed exceptionally well on these control puzzles, proving they were paying attention to the wording and not just guessing randomly. Finally, the students took a standardized test designed to measure their general cognitive ability using complex visual patterns.
When looking at the results, the researchers found distinct differences between the age groups. The older adolescents provided more mathematically correct answers than the younger adolescents during the fast, instinctive phase of the test. Under extreme time pressure and distraction, the older students were better at using the statistical numbers rather than falling for the stereotype.
Allowing the students extra time to think also produced different outcomes based on age. The twelfth graders improved their scores when given unlimited time to review the puzzle. The extra time allowed them to catch their mistakes and switch from a stereotypical answer to a mathematical one.
The seventh graders did not experience the same benefit. Their scores remained relatively flat between the fast and slow phases of the experiment. Taking extra time to ponder the problem did not guide the younger students toward the statistically correct answer.
The lack of improvement among younger students during the slow phase is particularly informative. It suggests that they do not yet possess the underlying mental strategies needed to override a basic stereotype. Even with infinite time to consider the numbers, the adolescent brain defaults to the descriptive narrative.
The researchers also looked closely at how general cognitive ability related to puzzle performance. For the older teenagers, higher cognitive ability scores predicted a specific behavior. Smart twelfth graders were the most likely to use the extra time to fix a wrong initial instinct.
Unlike adults, the older teenagers’ cognitive ability scores were not strongly linked to having a correct initial instinct. This means the immediate problem solving profile seen in adulthood has not fully matured by the end of high school. The older teenagers still rely heavily on their intelligence to fuel slow, deliberate corrections.
For the seventh graders, cognitive ability scores did not predict exact puzzle performance at all. The smartest adolescents in the younger group did not perform appreciably better than their peers on either the fast or slow phases of the test. The relationship between cognitive ability and accurate reasoning was not statistically significant for this younger age bracket.
The study authors suggest these results point toward a gradual optimization of logical rules. When children first learn about fractions and probabilities, applying those concepts requires intense mental effort. As they progress through middle and high school, they get thousands of hours of academic practice.
Through prolonged exposure, the rules of logic eventually become second nature. By the twelfth grade, students are starting to internalize these concepts, leading to slightly better gut instincts. Yet, the transition is still ongoing.
The seamless translation of high cognitive ability into instant, error-free logic appears to be a hallmark of adulthood rather than adolescence. The study does have a few limitations that leave room for future exploration.
The researchers originally included a second type of logic puzzle, the famous bat and ball problem. Participants are told a bat and a ball cost a specific amount together, and the bat costs exactly one dollar more than the ball. That puzzle proved too frustratingly difficult for both age groups, producing too few correct answers to analyze properly.
Future experiments will likely need to include a wider variety of reasoning problems to confirm these educational trends. Researchers could also benefit from testing these specific cognitive thresholds across different cultures and school systems.
The ability to generate a swift, rational answer does not emerge overnight. The research demonstrates that sound judgment is a skill that develops slowly over many years of education and life experience.
The study, “Emergence of the smart intuitor: how cognitive ability shapes adolescent reasoning,” was authored by Laura Charbit, Esther Boissin, Matthieu Raoelison, and Wim De Neys.
