Stress affects our motivation – but not necessarily our ability – to do difficult tasks

Three women in business attire, one being interviewed by the other two
Image by Tim Gouw / Unsplash.
Published: 24 September 2021

Stress increases people’s tendency to avoid cognitively demanding tasks, without necessarily altering their ability to perform those tasks, according to new research from McGill University.

“Generally speaking, people are demand-averse,” says Ross Otto, an assistant professor of psychology at McGill and the senior author of a recent paper in Psychological Science. “[Our study showed] stress increases that aversion.”

Study participants had to choose between repeating a single task over and over, or the more cognitively demanding process of frequently switching from one kind of task to another.

"Frequently switching between two simple tasks, such as moving between working on a spreadsheet and responding to emails, requires a greater level of effort than, say, performing just one of these simple tasks, or having to switch between the two tasks infrequently,” explains Otto.

“For example, consider a day where email notifications constantly pop up, indicating you need to change tasks and respond to that email, versus a day where you receive few emails, meaning fewer times you need to switch tasks. It’s not hard to imagine that one of these situations is more demanding than the other”

To see whether participants made different choices when they were stressed, the researchers used a scenario resembling a job interview to induce a stress response in half of the study participants. They then compared the choices made by individuals under acute stress against those of a control group.

While previous research has demonstrated that cognitive performance declines when we are under stress, the McGill study aimed to tease out the respective roles of motivation and ability in that equation.

“The interesting thing is the stress effects didn’t come out in performance,” Otto says. “So, it's not that the study participants were worse at either the more demanding or the less demanding task – their performance was no different; it’s just that when you give them the choice of whether they want to do one or the other, stress increases their unwillingness to invest effort.”

The experiment

In the experiment, participants were shown a series of numbers, coloured either blue or yellow. If it was one colour, they had to say whether the number was odd or even; if it was the other colour, they had to say whether the number was greater or less than five. The experiment was designed in such a way that participants were given cues which they would soon discover allowed them to choose which way the tasks were going to go – lots of repetition (less demanding) or lots of switching (more demanding). The participants’ response to these cues was what the researchers measured as an indicator of willingness to engage in cognitively demanding tasks – most people preferred the less demanding option, but they preferred it even more when they were stressed.

About the study

Acute Psychosocial Stress Increases Cognitive-Effort Avoidance” by Mario Bogdanov et al. was published in Psychological Science.


The research received funding from the German Academic Exchange Service, the Natural Sciences and Engineering Research Council of Canada, the Fonds de Recherche du Québec (Nature et Technologies), and the Canadian Foundation for Innovation.

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