People with higher intelligence make more accurate predictions about their lifespan

People with higher intelligence are better at making accurate predictions about their own futures, according to new research published in the Journal of Personality and Social Psychology. The study found that individuals with higher IQs consistently made more realistic forecasts about how long they would live, compared to people with lower IQs. These findings suggest that intelligence plays a direct role in shaping the quality of our beliefs about the world, and may help explain why lower intelligence is often linked to poor financial decisions and other judgment errors.

IQ, short for intelligence quotient, is a standardized measure of a person’s cognitive abilities, such as memory, problem-solving skills, reasoning, and verbal comprehension. It is usually assessed through a series of tests designed to measure a person’s mental performance relative to others. While the concept of IQ is sometimes debated, it remains one of the most widely used tools for evaluating general cognitive ability. IQ scores are often used in research to study how intelligence influences various life outcomes, including health, income, education, and decision-making.

Chris Dawson, a professor of economics and behavioral science at the University of Bath, conducted the study to explore whether intelligence is linked to the accuracy of people’s probabilistic judgments—specifically, how well individuals can estimate the likelihood of uncertain future events.

While many theories in psychology and economics assume that better decision-making depends on accurate beliefs about the world, few studies have directly tested whether IQ affects how well people can form these beliefs. Dawson’s work aimed to fill this gap by examining whether people with higher intelligence are more “calibrated” in their predictions—meaning their beliefs are closer to statistical reality.

Accurate beliefs are important because they guide decisions that affect our health, finances, and well-being. For example, someone who accurately estimates how long they will live may be better at planning for retirement or making decisions about savings and insurance. In contrast, someone who consistently overestimates their future lifespan might save too little or make poor health decisions. By studying how IQ relates to these predictive abilities, Dawson hoped to better understand one of the psychological mechanisms linking intelligence to life outcomes.

“There is huge amount of research looking at how people deviate from rational thinking models (like expected utility theory, where rational people weight up the probability of a decision leading to good/bad outcome and the pleasure/pain from these potential outcomes),” Dawson told PsyPost. “However, little evidence has focused on people’s ability to assess the probabilities of uncertain events, a central input into rational decision making.”

To test this question, Dawson used data from the English Longitudinal Study of Ageing, a nationally representative panel of adults in England over age 50. The sample included 3,946 participants who were interviewed multiple times between 2002 and 2019. Across these nine waves of data collection, participants were repeatedly asked to estimate their chances of living to a certain age (such as 75 or 85), depending on how old they were at the time.

These subjective probabilities were compared to statistical forecasts based on national life expectancy data, allowing the researcher to calculate how far off each person’s prediction was from what actuarial tables would suggest. These differences were used to measure each person’s forecast error, or the gap between their belief and the most likely reality.

IQ was measured using a broad range of cognitive tasks. These included memory tests, number puzzles, executive function tasks, word recall, semantic fluency, and other mental exercises. The scores were combined into a composite IQ score for each participant, referred to in the study as “phenotypic IQ.” In addition to this behavioral data, Dawson also used participants’ genetic data to calculate polygenic scores—estimates of each person’s genetic predisposition toward higher IQ or greater educational attainment.

The results showed a strong and consistent relationship between IQ and the accuracy of probabilistic judgments. People with higher phenotypic IQs made predictions that were closer to reality, both on average and over time. In statistical terms, a one-standard-deviation increase in IQ was associated with a nearly 20% reduction in the size of forecast errors. High-IQ individuals were not only less biased in their predictions but also less noisy—that is, their estimates varied less from one occasion to another.

“Estimating probabilities accurately leads to better decision making and therefore better outcomes for individuals,” Dawson explained. “For instance, if you overestimate the probability of a business idea succeeding, you may waste all your resources starting a business destined to fail. If you underestimate the probability of dying from lung cancer, you may decide not to quit smoking. Being realistic is important and people should try and be realistic in all aspects of decision making.”

To support a causal interpretation, Dawson used a method called Mendelian randomization, which leverages the randomness of inherited genetic traits. By using polygenic scores for IQ as instrumental variables, the study was able to show that genetically influenced differences in IQ predicted the accuracy of people’s forecasts. The analysis also used a similar approach with genetic scores for educational attainment, which include both cognitive and noncognitive traits. While these scores were also linked to better calibration, the effect was weaker than for IQ alone, suggesting that intelligence itself plays a central role.

Dawson also looked at “noise”—the variability in a person’s predictions across time. Even when asked the same question at different points, lower-IQ individuals showed much more inconsistency in their responses. For example, someone with low IQ might give very different answers about their chance of living to age 80 depending on the day they are asked, while a higher-IQ person would give more stable answers that remain close to the statistical expectation.

These findings support the idea that intelligence helps people form beliefs that are not only more accurate but also more stable. That matters because noisy or inconsistent beliefs can lead to poor decisions even if they’re not systematically biased in one direction.

“I have a study that shows that lower IQ leads to people being a bit more optimistic than usual about their future,” Dawson noted. “I thought in the current study lower IQ people may also display this optimism bias, but actually they were just more wrong in both optimistic and pessimistic directions.”

The study included a wide array of control variables. These covered demographic factors like age and sex, as well as health, wealth, education, and the socioeconomic status of the participants’ parents. This allowed Dawson to isolate the specific influence of intelligence on forecast accuracy, independent of other life circumstances.

But like all research, it was not without limitations. One issue is that all participants were over age 50 and lived in England, so the findings may not generalize to younger populations or people in other countries. In addition, even though Mendelian randomization helps to rule out some confounding factors, it cannot prove causation beyond all doubt. There could still be unknown environmental or cultural variables that influence both intelligence and prediction accuracy.

“The sample is on an older cohort of individuals tested on a specific probabilistic task (i.e., life expectancy),” Dawson said. “I see no reason to suspect that this result would not hold for younger people or different probability tasks, but I have no evidence for this.”

Despite these caveats, the study sheds light on an important psychological link between intelligence and decision quality. By showing that higher IQ is associated with more accurate and consistent probabilistic beliefs, the research suggests that cognitive ability may play a key role in shaping how people perceive the world—and by extension, how effectively they navigate it.

“I’m currently working with one of my PhD students (Yuyuan Wang) in assessing how low and high IQ types incorporate their probabilistic expectations into their decisions,” Dawson added. “Early evidence suggests high IQ people invest more for their retirement if they expect to live longer (this is rational as if you expect to live longer you need more resources for retirement). However, low IQ people don’t seem to use probabilistic expectations in their decision making. For this group, there was no relationship between life expectancy expectations and savings/investments for retirement.”

The study, “IQ, Genes, and Miscalibrated Expectations,” was published online on June 12, 2025.