Sense and sensitivity shape our experience of effort

Sense and sensitivity shape our experience of effort

We hear a lot of talk about “effort” and the “cost” of doing things. I’ve used those words a lot on this site, especially about determination. Cost decisions affect our intentions to take actions. But what do we actually know about the neurobiology of effort and intention?

Beyond sense and sensitivity

Our perception of effort influences whether we start, continue, or stop doing things. If we’re working out and find that something takes less effort than it should, we may be working harder. Or if it’s too hard, we can either take it down or stop it.

What if you did an experiment where you objectively measured how strongly people performed an action, then asked them to measure their relative sense of exertion, and also did brain scans to estimate neurotransmitter levels? Well, you don’t have to, because Eric J. Hu and colleagues from Baltimore, Dallas and London did this clever study.


More than 30 participants did a handgrip task that helped show that variability in exertion was associated with an inflated perception of exertion. In other words, when the outcome was less consistent, people found the task more difficult. This was linked to the activity of the neurotransmitter GABA, the major inhibitory neurotransmitter in the brain, which moderated performance variability and perceptions of exercise overestimation. Basic characteristics of motor performance and sensorimotor
neurochemistry therefore has a strong influence on ‘cognitive processes related to feelings of exertion’.

In a way, it’s as if the mismatch between what people planned and what they achieved made the task more difficult. The researchers put forward the interesting suggestion that people who have a better sense of their own actual performance have less sense of exertion. Perhaps with training people can get better at tuning ‘their nervous system to their desired sensorimotor output’. This work also emphasizes the importance of objective and measurable assessments of performance, as there may be weak associations for some.

Observing is believing

In a sense, we can see our sense of exertion as the psychological equivalent of intensity, which is influenced by our intentions. This is weighed against how successful we experience our efforts to achieve our goals.

This makes me think about what it’s like to learn a motor skill. For example, consider a long range of motion in martial arts, where the use of patterns and shapes is often found. When learning a form, it feels like it takes so long to complete; it seems to be extremely exhausting, and you feel like you have mixed success with each repetition. Basically, you feel like you’re making a lot of mistakes, and it feels very difficult and challenging. As you gain more skills, the variability of your performance decreases, the form seems easier and the time it takes to execute them seems much shorter.

Understanding this is critical to a better understanding of human behavioral choice. That’s because how difficult something appears to be is a key factor in how we judge whether it’s worth doing; the mental calculus of risk, reward, benefit, and effort. The point is that if we do something new, it will feel harder than it will feel later. But that “difficult” is part of the process of getting “easier”, and we must be vigilant that such temporary discomfort does not deter us.

(c) E. Paul Zehr (2022)


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