Inattentional blindness

Inattentional blindness

Inattentional blindness, also known as perceptual blindness, is when a person fails to notice some stimulus that is in plain sight. This stimulus is usually unexpected but fully visible. This typically happens because we are overloaded with inputs. It is impossible to pay attention to every single input we are presented with. Our attention cannot be focused on everything, and therefore, we all experience inattentional blindness. Sometimes, people falsely believe that they do not experience inattentional blindness. This is due to the fact that they are unaware that they are missing things. Inattentional blindness also has an effect on our perceptions. There have been multiple experiments performed that demonstrate this phenomenon. As a result, there are proposed reasons and ways to prevent this from happening. [1]


Experiments Demonstrating Inattentional Blindness

The term inattentional blindness was coined by Arien Mack and Irvin Rock in 1992. It was used as the title of Mack and Rock's book published by MIT Press in 1998. The book describes the discovery of Inattentional Blindness and the procedure used for revealing it.

Invisible Gorilla Test
The best-known study demonstrating inattentional blindness is the Invisible gorilla test, which was conducted by Daniel Simons of the University of Illinois at Urbana-Champaign and Christopher Chabris of Harvard University. Their study, a revised version of earlier studies conducted by Ulric Neisser, Neisser and Becklen, 1975, asked subjects to watch a short video in which two groups of people (wearing black and white t-shirts) pass a basketball around. The subjects are told to either count the number of passes made by one of the teams or to keep count of bounce passes vs. aerial passes. In different versions of the video a woman walks through the scene carrying an umbrella, or wearing a full gorilla suit. After watching the video the subjects are asked if they saw anything out of the ordinary take place. In most groups, 50% of the subjects did not report seeing the gorilla. The failure to perceive the gorilla or the woman carrying an umbrella is attributed to the failure to attend to it while engaged in the difficult task of counting the number of passes of the ball. These results indicate that the relationship between what is in one's visual field and perception is based much more significantly on attention than was previously thought. [2]

The basic Simons and Chabris study was re-used on British television as a public safety advert designed to point out the potential dangers to cyclists caused by inattentional blindness in motorists. In the advert the gorilla is replaced by a moon-walking bear.

Computer Red Cross Experiment
Another experiment was conducted by Steven Most, along with Daniel Simons, Christipher Chabris and Brian Scholl. Instead of a basketball game, they used stimuli presented by computer displays. In this experiment objects moved randomly on a computer screen. Participants were instructed to attend to the black objects and ignore the white, or vice versa. After several trials, a red cross unexpectedly appeared and traveled across the display, remaining on the computer screen for five seconds. The results of the experiment showed that even though the cross was distinctive from the black and white objects both in color and shape, about a third of participants missed it. They had found that people may be attentionally tuned to certain perceptual dimensions, such as brightness or shape. [3]

Clown on a Unicycle Experiment
One interesting experiment displayed how cell phones contributed to intentional blindness in basic tasks such as walking. In this experiment a brightly colored clown a unicycle traveled by. The individuals participating in this experiment were divided into four sections. They were either talking on the phone, listening to an mp3 player, walking by themselves or walking in pairs. The study showed that individuals engaged in cell phones conversations were least likely to notice the clown. This experiment was designed by Ira E. Hyman, S. Matthew Boss, Breanne M. Wise, Kira E. Mckenzie and Jenna M. Caggiano at Western Washington University. [4]

Blindness Despite Fixation
Daniel Memmert conducted an experiment which suggests that an individual can look directly at an object and still not perceive it.

In the experiment, which was based on the Invisible gorilla test, the participants were a group of children with an average age of 7.7 years. Participants watched a short video of a six player basketball game (three with white shirts, three with black shirts). The participants were instructed to watch only the players wearing black shirts and to count the number of times the team passed the ball. During the video a person in a gorilla suit walks through the scene. The film was projected onto a large screen (3.2 m X 2.4 m) and the participants sat in a chair 6 meters from the screen. The eye movement and fixations of the participants were recorded during the video and afterward the participants answered a series of questions.

Only 40% of the participants reported seeing the gorilla, leaving 60% who did not. There was no significant difference in accuracy of the counting between those who saw the gorilla and who did not. Analyzing the eye movement and fixation data showed no significant difference in the time spent looking at the players (black or white) between the two groups. However, the 60% of participants who did not report seeing the gorilla spent an average of 25 frames (about one second) fixated on the gorilla, despite not perceiving it. [5]

Effects of Expertise
Another experiment conducted by Daniel Memmert tested the effects of different levels of expertise can have on inattentional blindness.

The participants in this experiment included six different groups: Adult basketball experts with an average of twelve years of experience, junior basketball experts with an average of five years, children who had practiced the game for an average of two years, and novice counterparts for each age group. In this experiment the participants again watched the Invisible gorilla test video. The participants were instructed to watch only the players wearing white and to count the number of times the team passed the ball.

The results of the experiment showed that experts did not count the number of passes more accurately than novices but did show that adult subjects were more accurate than the junior and children subjects. A much higher percentage of experts noticed the gorilla compared to novices and even the practiced children. 62% of the adult experts and %60 of the junior experts noticed the gorilla, suggesting that the difference between five and twelve years of experience has minimal effect on inattentional blindness. However, only 38% of the adult, 35% of the junior, and none of the children novices noticed the gorilla, along with 18% of the children with two years of practice. This suggests that both age and experience can have a significant effect on inattentional blindness. [5]

Perception and Inattentional Blindness

In 1995, Officer Conley (Boston Police Officer) was put on trial for claiming he did not see a violent assault incident between a few people during the act of him chasing a suspect. Scientist accepted his alibi because of “intentional blindness” That is why he did not perceive the incident right away. This case now leads to an experiment. In this experiment, Psychology professors Christopher Chabris of Union College and Daniel Simons of the University of Illinois demonstrated with their students the same situations of the original incident of Officer Conley. During the experiment, they asked to go on a three minute run around the campus. They were then asked to focus on keeping a steady distance and a number of times he touched his head to wipe off sweat. While focusing on running and keeping a steady distance, the students then came across a staged fight ahead of their running path. During the staged fight, two students were jumping on one as they kicked, punched, yelled, and coughed. Most of the students missed the staged fight while running in the dark (in which officer Conley had his experience). During the day of the runners, 40 percent of the students still missed it. They all were so focused on running to the point they missed the staged fight. This is the same situation officer Conley was in.

Professor Chabris also stated that high physical exertion can also make a difference in your cognitive process. Officer Conley was involved with chasing a murder suspect during night hours watching him discard any weapons while running and any other activity.

Professor Simons stated that we can’t state with confidence that Conley didn’t see the fight during the suspect chase, but in result of the study, with less severe condition happening, it’s still even possible to miss something as obvious as fight, simply because of how you are directly concentrating on other things. [6]

Overall, perception can be affected while you are focusing on something else, it solely depends on the person as well as the type of event that is taken place. This all concludes to “intentional blindness”

Possible Causes

The research that has been done on inattentional blindness suggests that there are four possible causes for this phenomenon. These include: conspicuity, mental workload, expectations, and capacity. [7]

1. Conspicuity
Conspicuity refers to an objects ability to catch a person's attention. When something is conspicuous it is easily visible. There are two factors which determine conspicuity: sensory conspicuity and cognitive conspicuity. Sensory conspicuity factors are the physical properties an object has. If an item has bright colors, flashing lights, high contrast with environment, or other attention-grabbing physical properties it can attract our attention much easier. For example, we tend to notice objects that are bright colors or crazy patterns before we notice other objects. Cognitive conspicuity factors pertain to objects that are familiar to us. We tend to notice objects faster if they have some meaning in our lives. For example, when we hear our name, our attention is drawn to the person who said it. The cocktail party effect describes the cognitive conspicuity factor as well. When an object isn’t conspicuous, it is easier to be intentionally blind to it. We tend to notice items if they capture our attention in some way. If the object isn’t visually prominent or relevant, there is a higher chance that we will miss it.

2. Mental Workload
Mental workload has to do with how much a person has on their mind. Having a heavy mental workload can cause issues. Having too little of a workload can cause issues too. When we focus a lot of attention on one stimulus, we focus less attention on other stimuli. For example, talking on the phone while driving – your attention is mostly focused on the phone conversation, so there is less attention focused on driving. The mental workload could be anything from thinking about tasks that need to be done, or tending to a baby in the backseat. When we have most of our attention focused on one thing, we are more vulnerable to inattentional blindness. However, the opposite is true as well. When we have a very small mental workload – we are doing an everyday task – we tend to go into autopilot. In autopilot, we tend to do things without thinking about them. This can cause a person to miss crucial details and to become inattentionally blind to their surroundings.

3. Expectation
When we expect certain things to happen, we tend to block out other possibilities. This can lead to inattentional blindness. For example, you are looking for your friend at a concert, and you know she was wearing a yellow jacket. In order to find her, you look around for people wearing yellow. It is easier to pick a color out of the crowd than a person. However, if she took off her jacket, you could walk right past her and not notice because you were looking for the yellow jacket. Because of expectations, experts are more prone to inattentional blindness than beginners. Experts know what to expect when certain situations arise. Therefore, they will know what to look for. This could cause them to miss out on other important details that they may not have been looking for.

4. Capacity
Attentional capacity is a measure of how much attention must be focused on a task to complete it. For example, an expert pianist can play a piano without thinking much, but a beginner would have to consciously think of every note they hit. This capacity can be lessened by drugs, alcohol, fatigue, and age. With a small capacity, it is more possible to miss things. Therefore, if you are drunk, you will probably miss more than a sober person would. If your attentional capacity is large, you are less likely to experience inattentional blindness.


Inattentional blindness is exploited by illusionists in the presentation of "magic shows" in the performance of some tricks by focusing the audience's attention upon some distracting element, away from elements of the scene under manipulation by the performer. This is called misdirection by magicians.

See also


  1. ^ Most, S. (2010) “What is “inattentional” about inattentional blindness.” Consciousness and Cognition.
  2. ^ Chabris, C. Clifford, E. Jimenez, R. Most, S. Scholl, B. Simons, D. (2001) "How Not to be Seen: The Contribution of Similarity and Selective Ignoring to Sustained Inattentional Bindness." Psychological Science. Vol 12 No. 1.
  3. ^ Carpenter, Siri. (2001) “Sights Unseen.” Monitor on Psychology. Vol 32 No. 4.
  4. ^ Boss, M. Caggiano, J. Hyman, I. McKenzie, K. Wise, B. (2010) “Do You See the Unicycling Clown? Inattentional Blindness While Walking and Talking on a Cell Phone.” Applied Cognitive Psychology. 24:597-607.
  5. ^ a b Memmert, D. (2006) “The Effects of Eye Movements, Age, and Expertise on Inattentional Blindness.” Consciousness and Cognition. 15: 620-627.
  6. ^ Chabris, C. Fontaine, M. Simmons, D. Weinberger, A. (2011) “You do Not Talk About Fight Club if You Do Not Notice Fight Club: Inattentional Blindness For A Stimulated Real-World Assult.” i-Perception. 2: 150-153
  7. ^ Mack, A. (2003) “Inattentional Blindness: Looking Without Seeing.” Current Directions in Psychological Science. Vol 12, No 5 179-184.

Further reading

Mack, A. & Rock I. (1998) Inattentional Blindness. MIT Press

External links

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Inattentional Blindness — Blindheit wegen Unaufmerksamkeit oder Unaufmerksamkeitsblindheit wird in der englischsprachigen Literatur als inattentional blindness bezeichnet. Oft bemerken wir selbst größere Veränderungen an den Objekten in unserer Umgebung nicht… …   Deutsch Wikipedia

  • inattentional blindness —    The term inattentional blindness is indebted to the Latin words in (not) and attentio (attention, notice). It was introduced in or shortly before 1992 by the American psychologists Arien Mack (b. 1931) and Irvin Rock (1922 1995). It is used to …   Dictionary of Hallucinations

  • inattentional deafness —    The term inattentional deafness is indebted to the Latin words in (not) and attentio (attention, notice). It was introduced in or shortly before 1995 by the American psychologists Arien Mack (b. 1931) and Irvin Rock (1922 1995). It is used to… …   Dictionary of Hallucinations

  • blindness and hallucinations —    Visual hallucinations occurring in individuals with impaired vision have been reported since ancient times. Perhaps the best known historical example is the description of Charles Lullin s * visual hallucinations, as rendered by his grandson… …   Dictionary of Hallucinations

  • Change blindness — In visual perception, change blindness is a normal phenomenon of the brain which show in light that the brain does not have a precise representation of the world but a lacunar one, made of partial details. Despite the name, this phenomenon does… …   Wikipedia

  • change blindness —    A term used since the 1970s to refer to the relatively poor ability of humans to detect large changes to a visually perceived object or scene. Experiments making use of manipulated photographs, motion pictures, live interactions, and other… …   Dictionary of Hallucinations

  • Banner blindness — is a phenomenon in web usability where visitors on a website ignore banner like information.The term banner blindness was coined by Benway and Lane (1998) [ blindness.html] as a result of website… …   Wikipedia

  • Unaufmerksamkeitsblindheit — (auch Blindheit wegen Unaufmerksamkeit; engl. inattentional blindness) ist die Nichtwahrnehmung von Objekten, bedingt durch die eingeschränkte Verarbeitungskapazität des menschlichen Gehirns. Inhaltsverzeichnis 1 Überblick 2 Experimente von Mack… …   Deutsch Wikipedia

  • Daniel Simons — Fields Psychology change blindness inattentional blindness Visual attention Visual perception Institutions University of Illinois at …   Wikipedia

  • Dehaene-Changeux Model — The Dehaene Changeux Model (DCM), also known as the Global Neuronal Workspace or the Global Cognitive Workspace Model is a part of Bernard Baars s global workspace model for consciousness. It is a computer model of the neural correlates of… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.