If you haven’t seen the ignoble-winning work of Daniel Simons, take a look at this video. Concentrate on counting the number of times the people wearing white pass the ball. Try it on a friend. Pressure them to concentrate on the white team by re-inforcing how hard the task is and the necessity of counting all the passes but not the bounces. If they don’t know about the gorilla that walks through the basketball game, thumping it’s chest, chances are they won’t see it.
How can someone miss a large gorilla???? Obviously your eyes must “see” it, but it is never brought to your conscious attention. You only really consciously notice something if you are trying to see it, or it is new, interesting or dangerous. In the case of this video, you concentrate on the people in white, ignoring anything black. If you concentrate hard enough, you won’t see the gorilla. It’s part of the attentional bottleneck theory – that you only have finite resources and thus if you are really attending to something, you will not be able to process anything else.
And it’s not just videos. The same research team tested students at a university by having a “tourist” ask them directions on a map. Whilst giving directions, a couple of people carrying a door walked between the tourist and the person asked for directions. Whilst passing, the tourist changed places with one of the door carriers – thus leaving a different “tourist” to complete the discussion. Around 50% of people asked did not notice the change despite enormous differences in accent, clothing and appearance.
It seems ridiculous that we could evolve a sensory system that can’t see something like a gorilla, but it really isn’t. It’s a useful adaptation. Imagine walking into a room and being instantly aware of all the furniture, the paint, the title of every book etc. It would be overwhelming and pointless. Instead the sensory system has evolved to see only the things of importance in the room – the open champagne, the strawberries and the cute blonde (for example).
But ignoring too much is also dangerous – what if the gorilla was armed? Thus attention is a careful balance. Notice too much and you may overwhelm the senses – making it hard to see a lurking predator. Notice too little and the predator could be upon you in seconds.
Simons, D. J., & Rensink, R. A. (2005). Change blindness: Past, present, and future. Trends in Cognitive Sciences, 9(1), 16-20.
Simons, D. J., & Chabris, C. F. (1999). Gorillas in our midst: Sustained inattentional blindness for dynamic events. Perception, 28, 1059-1074.
Simons, D.J., & Levin, D.T. (1998). Failure to detect changes to people during a real-world interaction. Psychonomic Bulletin and Review, 5, 644-649