First: watch this video.
If the result failed to surprise you, congratulations. If it did surprise you, don’t worry. This video was made in 1999 by a pair of cognitive researchers, Daniel Simons and Christopher Chabris. Among those that they tested it on, half of them failed to see the gorilla. How is this possible?
Well, let’s start with a story.
An Unseen Fight
It was a cold winter night in 1995, and four men had just fled from the scene of a shooting at the Walaikum Burger restaurant in Boston. A radio call was sent out for assistance in the foot chase. Two of the approximately sixty officers who responded to the radio call that night were Michael Cox and Kenneth Conley.
Michael Cox sat in the passenger seat of the first car in pursuit–an unmarked police car. Seeing one of the suspects, Robert “Smut” Brown III, sprinting away towards a fence, he dashed out of the car and proceeded to chase on foot. Brown reached the fence first and frantically started to climb. Cox soon caught up, grabbed the suspect and tried to pull him back down. But Brown wriggled out of his grasp and jumped down the other side of the fence.
Cox was just about to follow the suspect over the fence when he was hit in the head from behind. He collapsed to the ground. Several police officers surrounded him and proceeded to kick him in the head and body.
Cox was in plainclothes that night. They mistook him for a suspect.
Kenneth Conley had arrived at the scene a few minutes earlier. He saw the suspect cross the fence, and followed in pursuit. A mile later, he caught up and arrested Brown.
It was only after Cox was beaten quite badly that someone recognized him and yelled for the others to stop. Upon realizing their mistake, the officers did not help him or call for help–they fled the scene.
For the next two years, investigations were conducted to uncover the people and motives behind the beating, but little information was found. None of the sixty or so officers on the scene admitted to knowing anything. Conley was one of these officers who denied any knowledge of the incident.
In court, Conley told the jury that despite having passed by the scene of the beating on his way to climb the fence, he did not see any beating happening. He claimed to experience “tunnel vision” during the chase, focusing solely on the suspect. In fact, even though Cox reportedly grabbed the suspect at the fence, he had not seen Cox at all.
The case progressed, and Conley was eventually charged with perjury and obstruction of justice. The jurors simply could not believe that he did not see the other officers beating Cox, and concluded that he was lying under oath.
What happened here? Did Conley really not notice the severe beating going on just a few paces from where he climbed the fence? Christopher Chabris and Daniel Simons, the researchers behind the “invisible gorilla” experiment, set out to demonstrate how it might be possible.
In 2011, years after Conley completed his 34-month prison sentence, Chabris and Simons set up a simulation of the incident. They asked participants to chase a running man while counting the number of times he touched his head; this would make the participants concentrate their focus on the man they were chasing. Then, at the site of the route, three men pretended to fight, with two of them beating the other.
The results were surprising: at night, only 35% of the participants noticed the fight. Even during the day, barely over half noticed.
This sheds some light onto Conley’s case. It is indeed plausible, and perhaps even likely, that he did not see the beating going on, especially given the time–2 a.m.–and the fact that his focus was on chasing down a sprinting criminal.
Arien Mack and Irvin Rock coined a term for this phenomenon back in 1992–inattentional blindness. The effect has been demonstrated many times since then, such as in the gorilla video at the beginning of this article. This also drives one of the main methods magicians use to fool us; through misdirection and sleight of hand, they draw our focus to less important things and rely on our own inattentional blindness to obscure the real action.
More generally, inattentional blindness is a form of selective attention, a theory that suggests that we can only focus on a narrow part of all that we sense. An example of this is seen in the “cocktail party effect”: despite being in a crowded room full of people talking over each other, we are able to distinguish and focus on a single voice. When we choose to focus our attention like this, we effectively “tune out” the other voices, even if something strange or interesting is being said. We can still pick up certain cues that stand out or are important to us, such as hearing our name–but even then, not all the time.
In a study by Wood and Cowan, participants were given headphones and asked to listen to the audio coming from the right ear. As the track played in the right ear, a separate one was played in the left ear, one in which the participant’s name was spoken multiple times. At the end of the study, only 35% of the participants recalled hearing their name.
This limitation of ours is precisely the reason why talking on the phone while driving can be quite dangerous. By distracting ourselves, we continuously shift attention back and forth between driving and talking, which lowers our response time or makes us completely miss traffic signals, billboards, cars, or other important things on the road.
We often expect our minds to see all that our eyes see, but this is often not the case. Our tendencies of selective attention and inattentional blindness mean we sometimes look at things without realizing what we are looking at, or miss things that we should be looking at.
In other words, sometimes we look, but do not see.
Next story: Hypnosis and Throwing Acid
“Sights Unseen.” Accessed March 25, 2013. http://www.apa.org/monitor/apr01/blindness.aspx.
Chabris, Christopher F, Adam Weinberger, Matthew Fontaine, and Daniel J Simons. “You Do Not Talk About Fight Club If You Do Not Notice Fight Club: Inattentional Blindness for a Simulated Real-world Assault.” i-Perception 2, no. 2 (2011): 150–153. doi:10.1068/i0436.
Chabris, Christopher, and Daniel Simons. The Invisible Gorilla: And Other Ways Our Intuitions Deceive Us. Broadway Books, 2011.
Mack, Arien, and Irvin Rock. “Inattentional Blindness.” Psyche 5 (1999): 3.
Macknik, Stephen L., Mac King, James Randi, Apollo Robbins, Teller, John Thompson, and Susana Martinez-Conde. “Attention and Awareness in Stage Magic: Turning Tricks into Research.” Nature Reviews Neuroscience 9, no. 11 (November 2008): 871–879. doi:10.1038/nrn2473.
Wood, Noelle, and Nelson Cowan. “The Cocktail Party Phenomenon Revisited: How Frequent Are Attention Shifts to One’s Name in an Irrelevant Auditory Channel?” Journal of Experimental Psychology: Learning, Memory, and Cognition 21, no. 1 (1995): 255.