If you’ve ever felt drained by intense mental effort, science now backs up your experience. A new meta-analysis, published in Psychological Bulletin, shows that mental tasks requiring effort are often accompanied by unpleasant emotions. From students solving tough problems to professionals tackling complex work, the study found that mental exertion leads to feelings of frustration and stress across a wide range of tasks. This may help explain why we tend to shy away from mentally challenging activities.
The idea that people tend to avoid effort is a long-standing principle in psychology. It’s a central part of what is often referred to as the “law of less work.” This principle, grounded in studies on animal behavior, suggests that when given a choice, individuals—like animals—opt for less effort-intensive ways to achieve the same goal. This concept has influenced several fields, from neuroscience to economics, where effort is seen as a cost to be minimized.
But there’s a gap in the research. While many studies have demonstrated that people prefer to minimize effort, fewer studies have examined the actual experience of mental effort. Is mental exertion inherently unpleasant, or are there conditions under which people might find mental tasks rewarding? This study aimed to answer the first part of that question by investigating whether people generally find mental effort unpleasant and how this aversion varies across different contexts.
“There’s a longstanding debate in psychology about mental effort,” explained study author Louise David, a PhD student at the School of Health Professions Education at Maastricht University.
“On one hand, it’s clear that people tend to avoid mental effort when they can—for example, aligned with Daniel Kahneman’s concept of ‘System 1’ thinking, where individuals prefer easier, more automatic ways of making decisions, people generally prefer the path of least resistance and avoid investing mental effort when not strictly necessary or not sufficiently rewarded.”
“However, there’s also an argument that people can learn to associate mental effort with positive rewards, like praise in educational settings. We were intrigued by this unresolved debate and sought to explore whether people generally dislike mental effort or can come to appreciate it under certain circumstances. To do so, we conducted a comprehensive review of prior research involving adults who engaged in mentally effortful tasks.”
To explore the relationship between mental effort and unpleasant feelings, researchers conducted a meta-analysis, a method that pools data from multiple studies to draw broader conclusions. They focused on studies that used the NASA Task Load Index (NASA-TLX), a self-report measure that asks participants to rate their perceived mental effort and frustration after completing a task.
In each of the studies included in the meta-analysis, participants were asked to complete a task and then rate both the mental effort they expended and the frustration or negative feelings they experienced while performing the task. The NASA-TLX uses a visual analog scale that ranges from very low to very high, allowing participants to score their experience on a continuum from 0 to 100.
The key variables in this study were mental effort, measured by the question, “How hard did you have to work to accomplish your level of performance?” and negative affect, captured by a question asking how much participants felt “insecure, discouraged, irritated, stressed, and annoyed.” These two measures allowed the researchers to quantify both the amount of effort participants exerted and the level of frustration or stress they experienced during the task.
The meta-analysis included 358 tasks from 125 studies, with data from over 4,670 participants. These studies came from a variety of fields, including psychology, ergonomics, and computer science. Participants were drawn from a wide range of populations, including American physicians, Indian fighter pilots, and Japanese students. The tasks varied in nature, but all required some level of cognitive effort, whether it was a computer-based challenge or a real-world simulation.
The primary finding of the meta-analysis was that mental effort is consistently linked to negative feelings across a wide range of tasks and populations. On average, participants who reported higher mental effort also reported more frustration, stress, and irritation. This suggests that mental effort, in and of itself, tends to feel unpleasant to people.
This effect was consistent across different types of tasks. Whether participants were engaged in repetitive or varied tasks, whether they had control over the task or not, and whether they received feedback on their performance, the relationship between mental effort and negative affect remained strong. Even tasks that involved working with others or that had significant real-world consequences, such as medical procedures or flight simulations, showed the same pattern. More effort resulted in more negative emotions.
“The main takeaway is that mental effort often feels unpleasant, regardless of the task or individual,” David told PsyPost. “Our study confirmed a strong and consistent link between mental effort and negative emotions, such as frustration or irritation. This suggests that, even in situations designed to be engaging or rewarding, people still find effort aversive. This insight could help us better understand why we often avoid mentally demanding tasks, even when they are important or rewarding in the long run.”
Interestingly, the study found some variation in the strength of this relationship across different geographic regions. In particular, the link between mental effort and frustration was weaker in studies conducted in Asia compared to those in Europe and North America.
Despite this regional difference, the association between mental effort and negative feelings remained robust across all the other factors the researchers examined. The level of education, work experience, task design, and even whether the task involved physical activity or was performed in a group setting did not significantly alter the relationship. Regardless of the specific conditions, mental effort seemed to feel unpleasant to most people, most of the time.
“We were surprised by how robust the association between mental effort and negative emotions was across different tasks and populations. Regardless of the type of task, even those that had game-like features or performance feedback, the negative feelings remained. Even people who had likely been rewarded for their mental effort in the past, such as university-educated individuals, still found effort unpleasant. We had expected to find some exceptions, but the association was remarkably consistent.
“One intriguing nuance was that people in Asian populations seemed to find mental effort slightly less unpleasant (but still unpleasant) compared to those in North America and Europe, which could for example be due to cultural differences in educational systems. However, this finding could also be due to other explanations such as different connotations of the word ‘effort’ across languages.”
While the study provides important insights, it is not without its limitations. The study focused primarily on tasks performed in controlled settings, such as laboratory experiments or simulations. While this allowed the researchers to draw clear comparisons across different tasks, it is possible that people experience mental effort differently in more naturalistic settings, such as at work or in school. Future research could explore how mental effort is experienced in real-world environments and whether different task contexts or social settings might change how effort feels.
Another interesting avenue for future research would be to explore whether certain types of rewards can make mental effort feel less aversive. For example, studies could investigate whether people who are rewarded for effortful thinking—either through praise, money, or a sense of accomplishment—find these tasks more tolerable over time. This could help shed light on how to encourage people to engage in mentally demanding tasks.
“I am currently doing research in which we try to better understand how perceived mental effort influences decision-making in learning,” David explained. “I am interested in how students make choices about their learning strategies, especially when these strategies are effective but feel effortful and how we can help them to use these effective but effortful learning strategies during their studying. The ultimate aim is to find ways to support students in adopting these more challenging strategies and help them to embrace the mental effort necessary for this. I hope to contribute to the development of educational practices that balance the need for mental effort with the motivation to engage in meaningful learning.”
The study, “The Unpleasantness of Thinking: A Meta-Analytic Review of the Association Between Mental Effort and Negative Affect,” was authored by Louise David, Eliana Vassena, and Erik Bijleveld.
