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I came across this new article about inattentional deafness which is inspired by another research on inattentional blindness.  It is quiet astonishing how our mind works. It must have happened to you at least once that you were looking for something, like someone in a crowd, concentrating hard on finding him/her and did not even notice that someone else is waving at you. Even though you were looking at their direction, you did not see them at all. This is the basic idea behind the term inattentional blindness.      

In 1999 Simons and Chabris created a simple experiment in which they have asked the participants to count the number of passes made between same basketball team members. There were white shirted basketball players and black shirted players. During the game a man dressed in a gorilla suit walked across the court.  Most people, who concentrated on counting the passes did notice the black gorilla on the court. The experiment shows that we are not able to process unexpected visual stimuli when we are paying attention to something else. Based on this experiment a new experiment checked our hearing under similar circumstances. They asked participants to pay attention to what is being said in a conversation between 2 men or a simultaneously occurring conversation between 2 women. The auditory clip sounded as if all four were standing normally in the same room and preparing for a party.   33 second into the scene another man walked into the room and said repeatedly I am a gorilla.

Only 30% of the participants who attuned into the women’s conversations noticed the man saying I am a gorilla; while 90% of those attuned into the men’s conversation notice the voice of the man saying I am a gorilla. The experiment shows that we also have inattentional deafness. The participants did not hear it due to their concentration on the details of the conversations and the perception of a particular gender voice.  Concentrating on a women voice caused them to turn out the men’s voices in the room and thus they were more ‘death’ to the odd sentences that were added in the background. Under normal conditions, thus if they not paying attention to something specific, the sentence I am a gorilla would have been easily heard. Those who choose to focus on the men’s conversation were more attuned to men voices and thus more easily detected the content. Without attention we may not perceive (inattentional blindness’) or hear( inattentional deafness) details from our environment. Without perception there is little chance for the data to get registrated nor memorizedin our brain. After hearing about the gorilla, the participates saw/heard the clip again and were surprised and shocked that they totally missed it. Indeed when you know what to look for the focus is on that detail then it is funny that anyone could have missed it.  

You could listen to the tape by clicking the link below. Now that you know about the experiment and what it represents it might seem ridiculous to you that most of the respondents did not hear it, but think about the phenomenon and actually realize how amazing it is that something so obvious could get unregistered by our brain once we are focused on something less. Does it not make you wonder what else we could be ignoring, are blind or death to that could possibly change the way we think, feel, behave, our whole life and we are not even aware of its existence?


Dalton, P. & Fraenkel, N. (2012). Gorillas we have missed: Sustained inattentional deafness for dynamic events. Cognition, 124,3, 367-72.

Simons, D. J. & Chabris, C. F. (1999). Gorillas in our midst: sustained inattentional blindness for dynamic events. Perception, 28, 1059-1074.