Your Face, Your Brain, Emotions and Botox

Faces tell stories. A smile of happiness; eyes that open wide in amazement; or a tightening of the forehead that accompanies intense anger; whatever the emotions we are experiencing, they are oftentimes written into our faces.Indeed, most emotions are associated with very distinct facial expressions, involving highly selective recruitment among the muscles of the face.
One of the primary roles our facial muscles play lays in conveying our emotions to others, and we are all natural experts at using our faces to add additional meaning to the words we use in conversation.
Still, our faces do even more than simply translate our emotional state to the outside world; they also read information from the outside world to us:
From the theoretical perspective of embodied cognition, cognitive activity and bodily perception are intricately linked, and even abstract thoughts take shape in the mind by drawing upon the more concrete physical realities of bodily experience. For example, it is not merely a coincidental figure of speech that makes us refer to the future as laying ahead and to the past being behind us, but people who think of the future actually lean slightly forward, and thoughts of the past accompany the physical expression of shifting one's weight backwards.  Likewise inducing forward or backward motion can make future or past thoughts more readily available.
Similarly, embodied cognition theory might suggest that processing emotion-related information should also recruit the bodily representation of these emotions; part of which involve the sensory feedback that our facial muscles send to the brain when we smile, frown, or make any of the other facial expressions that signify our emotions. And indeed, experiments in which people are asked to read and judge the meaning of sentences describing pleasant situations, do show that people are generally quicker at understanding emotional-language when they are holding a pen between their teeth while reading, and slower when try to hold a pen between their lips.
Whhat is the connection, you ask? It's because holding a pen between your teeth forces you to use many of the same muscles you would use in a smile, and holding a pen between your lips requires using muscles that would prevent a smile. Simply using these muscles appeares to subconsciously induce the corresponding emotional state, which then makes it easier (in the case of the smile) or more difficult to comprehend the description of a pleasant situation
So here's a question for you: If the nerves leading to your facial muscles are so important to your brain's ability to process emotion-related information, what might be the effect of injecting a neurotoxin into certain areas of your face? A neurotoxin that that causes temporary muscular denervation in order to decrease activity of specific muscle fibers? A neurotoxin such as botulinum toxin-A, generally referred to as cosmetic botox?
The answer to this question is now documented in the June edition of the Journal Psychological Science, thanks to an experiment by David Havas and colleagues. For their experiment they recruited 41 first-time botox recipients to read emotion-related statements; some describing happy states; others describing angry or even sad states. The researchers measured the time it took participants to understand the meaning of these sentences (participants pressed a button to indicate they were ready), and then immediately sent them off to receive their very first botox shot.
To give you an idea of the different types of sentences, a happy sentence would read

"The water park is refreshing on the hot summer day."

An angry one might read

"The pushy telemarketer won't let you return to your dinner."

And a sad one could read

"You hold back your tears as you enter the funeral home."

In receiving their botox treatment, participants were injected the nerve toxin into the corrugator supercilii muscle; the muscle that pulls the eyebrows down and inward when experiencing negative emotions, and one of the main culprits in producing vertical wrinkles on the forehead.
Since use of the currogator supercilii is associated with the experience of negative emotions, but not with the experience of happy emotions, embodiment theory would suggest that directed denervation through the use of botox would make participants slower at processing sad and angry sentences, but leave their ability to process happy sentences unaffected.
Two weeks after the botox injection, participants were therefore asked back into the lab, where they performed - and were timed on - the same sentence comprehension task as in the first session (sentences were randomized and counterbalanced over participants in both sessions).
The table below shows the statistically significant increase in processing time for the sad and angry sentence, as well as the basically unchanged processing time for happy sentences that David Havas and his colleagues found in the experiment.

The authors interpret these finding as a demonstration that

"blocking facial expression by peripheral denervation of facial musculature selectively hinders emotional-language processing. This finding is consistent with embodied-simulation accounts of cognition, according to which neural systems used in experiencing emotions are also used to understand emotions in language. The finding also offers evidence of a functional role for peripheral activation in processing emotional language, and it suggests a bidirectional link between emotion and language that is mediated in part by moving the face. Finally, the finding provides novel evidence supporting facial- feedback theories of emotion-related processing"

The paper offers further explanations of the possible mechanisms via which botox inhibits emotional-language processing and discusses the theoretical implications.
From a practical perspective, I should point out that - although statistically significant - the effect size is relatively small (around 200 ms). Also, it is not clear to me whether the effect would remain for long-term botox users, or whether their brains would become accustomed to the denervation of particular muscles and compensate for this. Nonetheless, this is an interesting finding that should give many people something to think about. I - for one - wonder what is so bad about wrinkles in the first place...