Definition

Inattentional blindness - a failure to notice unexpected but perceptible stimuli in a visual scene while one's attention is focused on something else in the scene.

Source: American Psychological Association (APA) Dictionary of Psychology

Decription

Inattentional blindness is a form of vision loss also known as perceptual blindness. It involves not noticing people, objects, or events within a person's line of vision because their attention has been diverted, i.e. missing something that is happening right before them.

Every person can be affected by inattentional blindness due to the fact that the amount of information that can be processed by the human brain at once is limited. When that limit is reached, the brain starts to filter out (unimportant) information and people start to not notice objects, people or events that are within their view or forget them immediately. This often happens when a person is focused on a particular part or aspect of the scene before them. A classic example is an experiment where the participants were observing two groups of people who were passing a ball and were instructed to count the number of passes. The participants focused so much on the counting that they failed to notice a person in a gorilla suit walking amongst the players.

Susceptibilty to inattentional blindness depends on a number of factors such as:

• Personal traits, i.e. people have different limits on the ability to process information.
• The person's current physiological and psychological state. For example, people under the influence of alcohol or under stress tend to be more affected by inattentional blindness.
• The amount and intensity of stimuli and distractions.

In many situations inattentional blindness is harmless. However, under specific circumstances, e.g. when driving, flying or providing ATC service, it has the potential to cause or contribute to an accident or an incident.

Prevention and Mitigation

While inattentional blindness is a human trait and thus cannot be eliminated, there are a number of measures that can reduce the risk of it happending or mitigate the consequences. Examples of these (in the field of aviation) are:

• Training and awareness. Pilots and controllers often work in teams of two (or more). Knowing the symptoms and effects of inattentional blindness can help other team members recognize the onset of inattentional blindness. Also, through training and experience, a person could recognize situations where they would be move vulnerable. This may enable them to either ask for help or execute a simpler plan that reduces their workload.
• Reducing distractions. Examples of this include:
  • Controllers making every effort not to issue clearances and instructions during take off and landing (unless there is a safety issue).
  • Filtering out unimportant information on the controller's situational display (e.g. labels of aircraft that are not supposed to enter the sector).
• Following procedures (e.g. checklists). This often reduces the risk of not noticing important information as procedures are generally designed to focus on the most important aspects and actions.
• Fatigue management. Generally, fatigue reduces the brain capacity. Therefore, getting enough sleep/rest before and within the duty period reduces the risk of inattentional blindness.
• Not performing duties when under the influence of medications that can decrease attention.
• Workload management, e.g.:
  • Procedure design can spread the workload over a period of time.
  • Appropriate sector management greatly reduces the risk of controller overload.

Incident Example