Washington, Jan 30 (IANS) Your facial expression may betray your thoughts or feelings. But it also impairs your ability to grasp written language bearing on emotions, says a new study.
The study reported on 40 people who were treated with botulinum toxin, or Botox. Tiny applications of this powerful nerve poison were used to deactivate muscles in the forehead that cause frowning.

The interactions of facial expression, thoughts and emotions has intrigued scientists for more than a century, says the study’s first author, University of Wisconsin-Madison (UW-M) doctoral psychology candidate David Havas.

Scientists have found that blocking the ability to move the body causes changes in cognition and emotion, but there were always questions.

Havas was studying people after a pinpoint treatment to paralyse a single pair of “corrugator” muscles, which cause brow-wrinkling frowns.

To test how blocking a frown might affect comprehension of language related to emotions, Havas asked the patients to read written statements, before and then two weeks after the Botox treatment.

The statements were angry (”The pushy telemarketer won’t let you return to your dinner”); sad (”You open your email in-box on your birthday to find no new emails”); or happy (”The water park is refreshing on the hot summer day.”)

Havas gauged the ability to understand these sentences according to how quickly the subject pressed a button to indicate they had finished reading it.

“We periodically checked that the readers were understanding the sentences, not just pressing the button,” says Havas.

The results showed no change in the time needed to understand the happy sentences. But after Botox treatment, the subjects took more time to read the angry and sad sentences. Although the time difference was small, it was significant, he adds.

The changes in reading time couldn’t be attributed to changes in participants’ mood, says an UW-M release.

The use of Botox to test how making facial expressions affect emotional centres in the brain was pioneered by Andreas Hennenlotter of the Max Planck Institute in Leipzig, Germany.

“There is a long-standing idea in psychology, called the facial feedback hypothesis,” says Havas. “Essentially, it says, when you’re smiling, the whole world smiles with you.”

The study is slated for publication in Psychological Science.