Scientists have found hard evidence that people detect and process grammatical errors with no awareness of doing so.
Neuroscientists from the University of Oregon in US recorded brain activity of the participants using electroencephalography, from which researchers focused on a signal known as the Event-Related Potential (ERP).
This non-invasive technique allows for the capture of changes in brain electrical activity during an event. In this case, events were short sentences presented visually one word at a time.
The participants were native-English speaking people, aged between 18 to 30.
Subjects were given 280 experimental sentences, including some that were syntactically (grammatically) correct and others containing grammatical errors, such as "We drank Lisa's brandy by the fire in the lobby," or "We drank Lisa's by brandy the fire in the lobby."
A 50 millisecond audio tone was also played at some point in each sentence. A tone appeared before or after a grammatical faux pas was presented. The auditory distraction also appeared in grammatically correct sentences.
This approach, said lead author Laura Batterink, a postdoctoral researcher, provided a signature of whether awareness was at work during processing of the errors.
The key to conscious awareness, she said, is based on whether or not a person can declare an error, and the tones disrupted participants' ability to declare the errors.
But, even when the participants did not notice these errors, their brains responded to them, generating an early negative ERP response. These undetected errors also delayed participants' reaction times to the tones.
"Even when you don't pick up on a syntactic error your brain is still picking up on it. There is a brain mechanism recognising it and reacting to it, processing it unconsciously so you understand it properly," Batterink said.
The study was published in the Journal of Neuroscience.
"The grammatical violations were fully visible to participants, but because they had to complete this extra task, they were often not consciously aware of the
violations," she said.
"They would read the sentence and have to indicate if it was correct or incorrect. If the tone was played immediately before the grammatical violation, they were more likely to say the sentence was correct even if it wasn't," she added.
When tones appeared after grammatical errors, subjects detected 89 per cent of the errors.
When the tones appeared before the grammatical errors, subjects detected only 51 per cent of them.