David Neal of the University of Southern California worked with a colleague from Duke University in North Carolina, USA Today reported. They published their findings in Social Psychology and Personality Science.
Botox paralyzes facial muscles, and Neal suggested having a less expressive face may make someone less able to read other faces.
Neal and his colleague worked with two groups of subjects. One tested 31 women who had been treated with either Botox or Restylane, a skin filler, and the other a somewhat larger group of women and men given a gel that amplifies muscle action.
The subjects were asked to say what emotions they saw on a group of faces.
"When the facial muscles are dampened, you get worse in emotion perception, and when the facial muscles are amplified, you get better at emotion perception," Neal said.
A study published last year suggested people who have been treated with Botox are less able to feel emotions.