In the 1980s, a study was done which concluded that long-married couples began to resemble each other over time, especially if they were happily married. So researchers at the University of Southern California and Duke wanted to see what the results would be if one had Botox, an injection that literally interferes with nerves and paralyzes muscles. The researchers found that mimicking another's expressions sends signals to the brain that enable us to empathize and better understand the emotions of the person we're conversing with. Those who had Botox injects physically could not mimic those expressions, which robbed them of the signals to the brain. The result was that, on average, Botox patients guessed 2 more out of 36 facial expressions wrong when compared to a group that could mimic expressions.
So what does this mean? Perhaps holding off on the important conversations right after your spouse has a Botox appointment. To read more about this study, check out this NY Times article.