As part of the study, participants were given either acetaminophen or a placebo for three weeks. None of the participants knew which one they were given. Each evening, participants completed a Hurt Feelings Scale, designed as a standardized measure of emotional pain. They were asked to rank themselves on statements such as: "Today, being teased hurt my feelings." It turned out that the pain medicine reduced reports of social pain.
The emotional dampening documented in these experiments is not huge, but it appears significant enough to nudge people into a less-sensitive emotional state.
Since that study was published in Psychological Science back in 2010, a body of evidence has accumulated that points to a range of subtle psychological effects attributed to acetaminophen. For instance, a study published in 2015 found that the pain medicine seems to diminish our emotional highs and lows. Another study pointed to a reduction in empathy among people taking acetaminophen.
And a study published in October suggests the drug may dampen the tendency to distrust in people with borderline personality disorder.
"Through reducing our attention to the outside world, acetaminophen appears to nudge us into a more psychologically insulated state," says Todd Handy, a psychology professor at the University of British Columbia in Canada.
Handy also studies mind-wandering. In one recent experiment, published in Social Cognitive and Affective Neuroscience, he and his collaborators found that acetaminophen seemed to make people care less about the mistakes they made when they zoned out. During the experiment, participants were asked to sit in front of a computer screen and complete a repetitive task. "Once every couple seconds, something flashes on the screen and you have to hit a button," Handy explains. "We try to bore people so they will actually mind wander."
Handy found that people taking the painkiller mind-wandered at about the same rate as people on the placebo, but their reactions were different. "When people on Tylenol mind-wander, they're shutting stuff out more effectively than people who aren't on Tylenol."
Now, whether these subtle effects are good or bad depends on the context. Baldwin Way, a professor of psychology at Ohio State University who has also published on the effects of acetaminophen, says that in some instances, the emotional dampening could work against us.
"If you're speaking to your romantic partner and their emotions are blunted," Way says, "and they react blunted and less emotional, that can probably have a negative effect."
On the other hand, say you're anxious about an upcoming medical procedure, social situation or a job interview, "maybe having blunted emotions can help you perform more effectively," Way says.