Why even try? Using brain science to answer one of life’s biggest questions
Brown University
The
assumption, by researchers and Netflix-bingers alike, is that the amount of
mental effort a person invests in a task is influenced by the reward they stand
to gain — so in this case, the effort results in a paycheck, and successful
efforts could result in ego-pumping praise from a supervisor, a bonus, a
promotion or perhaps even a new, higher-paying job.
But
what if the person doesn’t believe that their efforts matter, and the reward
will be the same no matter how hard they try? How does that person decide how
much effort to expend — if any at all?
New research from a team of Brown University researchers, published on Monday, Feb. 15 in Nature Communications, shows that the amount of mental effort invested in a task is influenced not just by what a person stands to gain, but also the degree to which that outcome will depend on their performance.
In three related
experiments, the researchers demonstrated that participants performed better on
tasks when there was a bigger potential prize and when
they felt like their efforts made a difference in earning that prize.
Importantly, the study also identified the neural activity associated with this kind of decision process. The findings can be used to explain motivation as well as to figure out what’s going on when someone is lacking in it, the researchers say.
“This
study sheds light on the neural circuits that drive motivation, which in turn
help us learn more about why people may have trouble getting motivated, whether
it be situational or chronic and due to depression or other disorders,” said
Amitai Shenhav, study author and an assistant professor of cognitive,
linguistic and psychological sciences at Brown. “This work helps us answer
bigger-picture questions such as how people perceive the incentives in their
environment and how they determine that their efforts are worthwhile.”
Previous
research has shown that people often expend more effort on a task when it
promises greater rewards. However, if the person thinks they’ll succeed or fail
regardless of their efforts, they may decide not to invest the effort. The
research team put this theory to the test by having participants — all college
students — perform a series of trials of a well-known psychological experiment
called the Stroop task, which involves looking at words shown in different
color ink and correctly naming the color of the ink even when it doesn’t
match with the word (for example, RED printed in green ink).
The
researchers varied the difficulty of the task and the expectations of
efficacy and reward. In high efficacy trials, participants were informed that
fast, accurate responses would always be rewarded, while in low efficacy trials
they were told that their performance would have no bearing on whether or not
they would receive the rewards on offer (as long as they provided some
response). Before each trial, participants were told whether they had the
possibility of receiving a low ($.10) or high ($1.00) reward. In one of the
experiments, the participants’ neural activity while they were performing the
trials was measured using EEG data.
The
trials were meant to emulate real-world decisions: While it’s sometimes easy to
draw a straight line between how much work you put in and how much reward
you’ll accrue (as with a quiz — studying increases the likelihood of success),
there are many situations in which this association is less direct.
“For
example, when applying to college or a new job, there are many factors that
might affect success, and only some of them are within an applicant’s control,”
said Romy Frömer, a postdoctoral research associate in Shenhav’s lab at Brown’s
Carney Institute for Brain Science, and a lead author on the study. “When faced
with all of these variables, we wondered: How do people decide the amount of
effort to invest?”
Confirming
the researchers’ predictions, the study found that participants invested the
most mental effort, and thus performed better at the task, when expecting
reward and efficacy to be high.
The
results also illuminated what was going on in the participants’ brains as they
considered how much effort to invest. Researchers were able to identify the
neural activity associated with first, how the participant evaluated both
elements of their incentives (reward and efficacy), and then, how much effort
they decided to invest.
“We
saw that participants used these two variables to inform their decision
about how hard they wanted to try on our task,” Frömer said. “Our work showed
how all of that happened before the required action took place — before
the person invested any cognitive effort.”
Frömer
and Ivan Grahek, also a postdoctoral research associate in cognitive,
linguistic and psychological sciences, have followed up on this work by using
EEG data to help explain how people learn about when their effort matters. This
body of research contributes toward a better understanding of how people
integrate their assumptions about efficacy into their decisions of how much
effort to invest.
The
research published in Nature Communications was co-led by Hause Lin, a
Ph.D. student at the University of Toronto. It was supported by a grant from
the National Institute of General Medical Sciences, an Alfred P. Sloan
Foundation Research Fellowship in Neuroscience and a grant from the
Natural Sciences and Engineering Research Council of Canada.
