Imagine you are reading an exciting book when someone taps you on the shoulder and says, “I’ve called your name five times and you didn’t answer!” but you did not hear anything. This phenomenon, called “inattentional deafness,” is likely familiar to many people. It occurs when an individual is so focused on a visual task, like reading, that he or she does not hear sounds nearby. A new study from University College London is the first to find that inattentional deafness has a neurological basis, affecting the processing of auditory input at a very early stage. The findings may have implications for people in jobs that require high levels of focus.
The researchers observed the brain activity of 13 volunteers using magnetoencephalography (MEG). The participants completed a visually simple and a visually demanding task while the researchers exposed them to sounds. Then, the researchers analyzed how the participants responded to the sounds when they were focused on the tasks.
The brain’s response to sound was markedly different when the participants were engaged in a visually demanding task compared to when they were not visually engaged. The participants had a higher failure rate in detecting sounds while they completed a visually demanding task. Their failure rate was high even though the sounds were audible. In contrast, the participants did well at detecting the sounds when the visual task was simple. The MEG data demonstrated that when the participants failed to detect sounds, it was not because they were ignoring them. In fact, the data showed that the participants did not hear the sounds at all.
The findings suggest that the brain has limited resources for processing auditory and visual input. The researchers say that the results have implications for people in visually demanding careers, like surgeons or drivers. The findings could have an impact on everyday issues, like pedestrians who tap out text messages while walking who are too engrossed to hear oncoming traffic.
This research is published in the Journal of Neuroscience.
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