Expectations for how coffee affects us might be enough to increase attention.
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Whether you like it black like your soul or you’re livin’ la vida mocha, coffee is a stimulant, and as such, drinking it increases our alertness. Whether it improves our performance on mental tasks depends on the situation. Still, there is a widespread belief among coffee lovers that the dark stuff helps them think clearly and work more efficiently.
And this belief is essential: in psychology and medicine, the placebo effect explains how sometimes our mere expectation that a substance—whether coffee or a pharmaceutical treatment—will help us in some way, people see actual improvement, even if there is no reason they should be experiencing improvement.
In drug trials, placebos, or pills that do not contain any medication, are often given to patients in the control group. In contrast, the actual drug is given to patients in the test group, and doctors compare their resulting symptoms. Even if you know you’re taking a placebo, taking a placebo can trick the brain into experiencing something different, even if there’s no medical reason for it. The same thing can happen in psychology: expecting that an event or stimulus will change your mood or attention or behavior can cause those changes. Even if there’s no scientific reason, you should be experiencing these changes.
What do placebos have to do with coffee? Two recent studies have examined the potential for coffee to have a placebo effect—specifically, they investigated whether simply being in the presence of coffee, even without drinking it, can have the same effects we expect to experience after drinking our morning cuppa.
Smell is a powerful sense, activating memories and providing a rich context for situations. Researchers in both studies wondered if smelling coffee was enough to trick people's brains into kicking into gear the way they expect them to when taking a sip.
A 2019 study by Hawiset randomly assigned participants to smell either coffee or carbon powder for five minutes and then tested both groups on a variety of cognitive measures, including attention, reaction time, word and picture recognition, spatial and numeric working memory, and alertness. They found that while people in the coffee group vs. the carbon group did not have initial differences in working memory, people who went on to sniff coffee before performing a second round of these tests scored higher on tasks related to attention, quality of memory, speed of memory, and alertness compared to their baseline. In contrast, the group that sniffed carbon had no significant improvement from their initial scores, and however, there was no difference in information processing speed.
To show that these effects were placebo effects and could not be explained by participants having the kinds of bodily reactions we would expect after ingesting a stimulant, Hawiset also measured participants’ blood pressure, heart rate, and cortisol levels before the big sniff. There was no difference in these physiological responses in either group compared to their baseline. In other words, it seems to be the idea of what coffee does for us, rather than anything changing in the body, that was responsible for the coffee-sniffers’ increased performance.
An earlier study further supported this idea. In 2018, Madzharov and colleagues tested the effect of coffee smell on performance. They compared people in an environment that smelled like coffee and one that was unscented. Both asked participants how well they expected to do on an analytical task and then performed that task. People in the scented room were expected to perform better on the job, and those expectations influenced their superior performance.
In a follow-up study, participants in the coffee-smelling room indicated specifically that they expected to be more alert in this environment, which would help them think and focus better.
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