I have long been intrigued by the fact that when I am absorbed in reading, I completely miss what people have said, even if they have been speaking directly to me. This can be embarrassing but in my case people tend to indulgently excuse it because of the stereotype of the ‘absent minded professor’. Being a theoretical physicist also helps since we are considered to be a little weird anyway.

But since I have been in the same room as the speaker, the sound waves must have entered my ears and gone to my brain but I have absolutely no memory of hearing anything. It is like the sound never even entered my head. This article explains why.

The researchers believe this deafness when attention is fully taken by a purely visual task is the result of our senses of seeing and hearing sharing a limited processing capacity. It is already known that people similarly experience ‘inattentional blindness’ when engrossed in a task that takes up all of their attentional capacity – for example, the famous Invisible Gorilla Test, where observers engrossed in a basketball game fail to observe a man in a gorilla suit walk past. The new research now shows that being engrossed in a difficult task makes us blind and deaf to other sources of information.

So it seems like we never really ‘hear’ anything until the brain has actually processed the incoming sound waves to register as sound. If the part of my brain responsible for this task is otherwise occupied, I haven’t really ‘heard’ it.

This has happened to me other than reading, when I am merely thinking about something and have tuned the speaker out. I am sure everyone has had the same experience of daydreaming and missing what was said. This adds to the evidence that certain kinds of multitasking are impossible at a basic cognitive level.