Compilation videos of Freudian slips by news anchors and politicians are good for laughs. Fumbling words while speaking or mixing up signs in ASL are natural occurrences. But what makes us jumble words and make speech errors? The errors take place due to a neural mechanism that is activated when the brain decides on what to say and observes how we say it.
Researchers at San Diego State University set out to study the mechanism leading to blunders in speech. The research’s finding could be used to improve rehabilitation therapy for patients trying to recover their speaking or signing ability following a stroke.
Previous studies have noted that healthy adult speakers commit a speech error once every 1000 words and the same holds true for deaf individuals using sign language. This efficiency in speech is carried out due to language monitoring processes in the brain which control the words we speak as we are speaking them. While the neural mechanism involved in producing clear speech has been studied in the past, they have been largely ignored when it comes to sign language.
In this study researchers used a picture-naming task and scalp EEG to determine that the language monitoring mechanism hosted in the medial frontal cortex is similarly engaged in signing as it is in speaking. The participants comprised of 21 hearing signers and 26 deaf signers.
“When we are doing an action, whether it’s speaking, signing, pressing buttons, or typing, we see the same mechanism. Any time we are making a decision to do something, this neural mechanism comes into play,” comments researcher Stephanie Ries.
The medial frontal cortex kicks in 40 milliseconds and it is thanks to the speech monitoring mechanism here that we catch ourselves before making an error. But words still get muddled some times and that may be due to us not selecting the right one when our brain presents us with semantically related words.
The study findings could help better understand how deaf individuals regain their ability to sign following brain damage. The scientists believe that stroke victims who are more aware of their errors while communicating have a better chance of recovery as they possess better speech monitoring mechanisms that help them improve.
Co-author Karen Emmorey was drawn to the study due to a longstanding fascination with “inner signing”. While we can hear ourselves when we speak, how do people using sign language perceive themselves as they communicate? Do they visualize themselves as a mirror image, use mental images of the signs or simply observe their gestures?
Gaining more insights into how sign language is presented in the brain could help researchers better understand sign language disorders and devise appropriate treatments. In the scenario that the person requires epileptic surgery, we would know which areas in the brain which should be targeted.
However, little tweaks in the brain region to turn ordinary individuals into excellent orators or rap geniuses; at the moment, remains a far fetched idea.
