Botox injections may help erase wrinkles and other signs of aging but according to a new study, the cosmetic procedure impairs the ability of a person to read other people's emotions.
Researchers at University of Southern California (USC) and Duke University found that women who received Botox injections in their face were less accurate in reading expressions of emotions like fear, worry, joy or sadness on faces of other people.
The study's lead author, USC psychology professor David Neal, said Botox's paralysing effect on facial muscles in the immediate vicinity of the injection site negatively affects a person's ability to read another's emotional state.
He said people identify emotions partly by mimicking each other's facial expressions.
"When you mimic, you get a window into their inner world," Neal said.
"When we can't mimic, as with Botox, that window is a little darker."
The researchers based their findings on two experiments.
The first involved 31 women who had received either Botox or Restylane, a dermal filler that smoothes wrinkles but does not affect facial movement.
In a second experiment, 56 women and 39 men were given a topical facial gel that functioned as an "anti-Botox" by augmenting signals from facial muscles.
The participants then looked at a series of faces on a computer screen and were asked to identify the emotions.
The researchers found that compared with the Restylane-treated control group, the women who got Botox were less able to read emotions based on facial expression.
Those who got the gel, perceived emotions much better than the other group.
With key areas surrounding the eyes immobilised by Botox, subjects were unable to reproduce fully the emotional expression of a person.
People use mimicry to register and label the emotional states of others, so a procedure like Botox that limits the ability to reproduce another person's expression of emotions would likely "impair our ability to register or label those emotions," Neal said.
"Our ability to read others' emotions isn't something that takes place solely in the head," Neal said.
"Our emotional intelligence does depend partly on our ability to listen to our own bodies, and if we don't or can't do that, our emotional world gets diminished."