There are days when even little things seem surprisingly difficult. Replying to a message. Taking a shower. Going shopping. Calling a friend back. These are small, everyday actions, often done in a few minutes. And yet, for many people, these sometimes feel like tasks for which they have barely enough energy.
When we see this kind of struggle in a friend or relative, or feel it in ourselves, simple explanations might come to mind: a lack of drive; a need for meaningful goals; laziness. You just need to pull yourself together. You know it would do you good.
This view overlooks something important. Between considering or intending to do something and actually doing it, there is a psychological process that usually remains invisible in everyday life. Colloquially, people call this process ‘motivation’. But motivation is not like an internal fuel tank that is full or empty. Rather, it involves a continually running cost-benefit calculation.
Our brains constantly analyse the extent to which an action is worth the effort, which informs us about the seemingly best option at any given moment. This process is called effort-based decision-making. Since the workings of this process are usually hidden, it’s easy to make wrong inferences about the reasons for a person’s choices or inactivity.
However, scientists have devised ways to observe this process in action, allowing us to learn more about what’s happening when a person weighs doing or not doing something. Understanding this process encourages more helpful attitudes toward those who struggle with everyday motivation, which is often connected to a broader mental health condition. It can also inform the best ways to help someone overcome their challenges.
The analysis of costs and benefits usually takes place so quickly that we barely notice it. Should I answer this email now or put it off until later? Should I exercise after work or rest on the sofa? Should I meet my friends tonight even though I’m already tired? To answer these questions, our brains (and, actually, the brains of all vertebrates) weigh three things against each other. How effortful will it be for me to achieve this goal? How rewarding will it be for me – enough to outweigh the costs? And how likely is it that the reward will actually occur?
Most of the time, this process is very helpful. It prevents us from becoming completely exhausted, from being constantly disappointed, or from wasting our time and effort. But the cost-benefit analysis can also go wrong. From the outside, this can look like laziness or indifference, and it often results in difficulties managing work or school activities, relationships or self-care routines.
Altered cost-benefit calculations seem particularly relevant in the context of conditions such as depression, bipolar disorder and schizophrenia. In people diagnosed with these disorders, motivational difficulties are common. While other symptoms of these disorders might be better known – eg, sad mood in depression, mood swings in bipolar disorder, or delusions and hallucinations in schizophrenia – motivational problems commonly pose the strongest long-term barrier to wellbeing. They often persist beyond the acute phases of the illness and are currently considered difficult to treat. As a result, they can have a lasting impact on daily life. When someone struggles to take the necessary steps to keep up with a friend, go to appointments or apply for a job, for example, it can lead to a downward spiral in terms of social participation, wellbeing or professional opportunities. These experiences often prompt negative self-evaluations (such as: I’m a complete failure), which can further exacerbate someone’s motivational problems.
The internal cost-benefit calculation seemed to have become unbalanced in people with these disorders
The concept of effort-based decision-making allows researchers to look behind the scenes and better understand the mechanisms underlying these motivational problems at the moment of choice. To do this, researchers use computer-based tasks that are designed to isolate the decision-making process as precisely as possible.
In a typical study, a person has to choose between an easier task and a more difficult one. The easy task might consist of pressing a button 30 times with the index finger of the dominant hand in order to receive a small reward, such as one dollar. The difficult task might involve pressing a button 100 times with the little finger of the non-dominant hand, but receiving a larger reward in return. Across repeated trials, the size of the reward for the difficult task changes. In some versions, the probability of receiving the reward also changes: one might have, for example, a 12 per cent, 50 per cent or 88 per cent chance of receiving the reward for a task. Sometimes even the amount of effort required for a given reward varies. Before each decision, participants see how much effort is required for a task, what reward is possible and how likely it is that they will receive this reward. Then they decide what to do. The outcome of interest is when someone decides that the more difficult task is worth it.
In a recent meta-analysis, my colleagues and I summarised the results of 68 studies on effort-based decision-making in mental disorders. We found a clear pattern showing that people with schizophrenia, depression or bipolar disorder were less likely than people without these diagnoses to choose effortful actions in order to obtain a reward. This reduction was most pronounced in schizophrenia and bipolar disorder and smaller, but still statistically significant, in depression.
Typically, when a reward becomes larger or more likely to be attained, people invest more effort. It seems more worthwhile. In clinical groups, however, this adjustment was weakened. People with schizophrenia, depression or bipolar disorder did not increase their effort to the same extent as others when rewards became larger or more certain. Their internal cost-benefit calculation seemed to have become unbalanced.
At first glance, this speaks to a common motivational problem across different diagnoses. However, the story gets even more interesting when we examine why this happens.
One way to approach this question is through computational modelling. In this statistical method, a computer model is used to try to reproduce a person’s decisions by testing different explanations for their behaviour. Let us imagine several people who rarely choose the more difficult task over the easier one. One person may avoid the task because the effort feels particularly burdensome to them. Another may avoid it because the reward has little motivating force for them. A third person might primarily have difficulty bringing all the information together and translating it into an informed decision. Computer-based models help researchers distinguish between these possibilities, which is important for understanding where the cost-benefit calculation goes wrong.
Our review of computational modelling studies suggests that the motivational problems in different mental disorders arise in partly different ways. For people with schizophrenia, the results often indicate that amounts of effort, reward and probability of receiving the reward are all less influential for decision-making. The difficulty seems to lie in integrating and processing multiple pieces of information in a situation and making them usable for one’s own decisions. This fits with the findings of our meta-analysis, according to which cognitive difficulties – in working memory or processing speed, for example – are associated with alterations in effort-based decision-making in schizophrenia.
A person experiencing mania might work through several nights, the effort not feeling burdensome at all
When it is difficult for someone to keep relevant information in mind, update it and compare it with other information, then decision-making becomes more difficult. For example, if someone with schizophrenia wants to return to work and needs to decide whether to apply for a particular job, even taking the first step requires weighing several bits of information: the effort involved in starting an application or making a phone call, the potential benefits of applying and the likelihood that they will get a job offer. If all the relevant information can’t be readily integrated into a cost-benefit calculation, this might feel overwhelming. Instead the person may choose less demanding options or postpone taking action.
In depression, the picture looks somewhat different. Here, studies using computational modelling often suggest that effort carries special weight. The reward may still be attractive, but the path to it feels too effortful to seem worthwhile. A person may know that it could do them good to meet up with a friend, for instance. Perhaps they even expect that they will experience some pleasure from it. And yet getting dressed, leaving the house, getting there and having a conversation might feel like daunting obstacles.
In bipolar disorder, the evidence base is more limited. The current illness state probably plays an important role. In more stable phases, people with bipolar disorder may still be able to weigh effort, reward and probability relatively well. In depressive phases, their pattern resembles that seen in depression, with effort being experienced as particularly burdensome. In manic or hypomanic phases of the disorder, the problem could manifest in a dysregulated willingness to exert effort in situations where reward and probability are actually low. For example, a person experiencing mania might work through several nights on a business plan and sell various belongings to invest in the plan because, to them, the potential reward seems extremely high, and the effort does not feel burdensome at all.
These differences suggest that there is not one solution for all motivational problems. For some people, it may be helpful to make rewards more concrete, more immediate and more emotionally tangible. For example, ‘Seeing friends is good for me’ might become: ‘After 10 minutes of conversation, I usually feel a little less alone.’ For others, the critical change might be to reduce the felt costs of an action, such as by breaking down a task into smaller steps. Still others may need support with planning, or with comparing effort and reward more clearly and meaningfully.
Some existing therapeutic approaches use techniques that may act on these mechanisms. Positive affect treatment focuses on helping people look forward to rewarding experiences and engage more fully with positive events. Cognitive behavioural social skills training includes problem-solving modules that involve dividing planned activities into smaller steps. Cognitive remediation programmes aim to strengthen abilities such as attention and memory, which are needed to weigh effort against possible rewards. The next step is to bring together methods like these into a more comprehensive treatment that addresses the specific reasons why activities feel unrewarding or difficult, and that can be tailored to each person’s needs.
Sometimes, inactivity is the visible result of an invisible calculation that has become unbalanced
The effort-based decision-making lens can also inform how we respond to motivational problems in ourselves and others. Things like ‘You just have to start’ or ‘Once you do it, you’ll feel better’ can be frustrating to hear because they imply that the problem is simply a lack of willpower. A curious, empathic attitude is likely to be more helpful. What exactly feels difficult? Is the effort too great? Is the reward too far away? Is the outcome too uncertain? Is the task too complex to plan? Such questions are more helpful than just telling someone to make an effort or pointing out that it will be worth it in the end.
Motivation is not a fixed character trait, but a dynamic process, one that changes with mood, context, cognition, symptoms, exhaustion, social support and expectations. This insight is not relevant only for people with mental disorders. Everyone has moments when the internal calculation tilts one way or the other. Consequently, the email stays unread, the sports shoes sit by the door or the call from a friend goes unanswered. When in doubt, we might accuse ourselves of being weak or undisciplined. But perhaps it’s really that the reward is not clear enough, the task seems too effortful or the prospect of success feels too doubtful. Sometimes, inactivity is the visible result of an invisible calculation that has become unbalanced. This is a problem that calls for attention rather than criticism.