Motion blindness facts for kids

Imagine not being able to see things move, even though you can see them perfectly when they're still! This rare condition is called motion blindness or Akinetopsia. People with motion blindness can see objects clearly when they are not moving, but they cannot see them in motion. For example, a car might appear in one spot, then suddenly be in another, without the person seeing it drive between the two points.

This condition is very rare and seems to be linked to how the nerves in the brain work. It might also be related to how the brain processes information. Right now, there is no known treatment for motion blindness. Most of what we know about it comes from studies of a few patients between 1913 and 2003. A lot of important information comes from one patient, a woman known as LM. She was 43 years old when she had a stroke in 1978, which led to her condition.

Scientists believe motion blindness happens because of changes in the parts of the brain responsible for sight. These changes usually come from damage to the brain. This damage affects how the brain "decodes" or understands what the eyes see. It's thought that only the "visual" part of motion processing is affected because this happens in a specific area of the brain. This is different from how the brain handles motion in general. A similar thing can happen with seeing colors, where a person might have a type of color blindness called achromatopsia. Unlike most color blindness, which comes from problems with the eyes, this type is caused by changes in the brain.

What is Motion Blindness Like?

People with motion blindness usually have normal vision in other ways. They can see objects clearly, know how far away things are, and see different colors. This is true for shapes, objects, and even faces. However, they simply cannot see these objects move.

Besides not seeing movement, akinetopsia also makes it hard to do everyday tasks that need you to see things moving. For example, reaching for something or catching a ball becomes very difficult. It seems that being able to see your own movements is also important for these tasks.

Daily Challenges

Patients with motion blindness face many challenges in their daily lives. LM, the patient mentioned earlier, described how hard it was to pour a cup of tea or coffee. She said the liquid looked "frozen, like a glacier." She didn't know when to stop pouring because she couldn't see the liquid rising in the cup.

LM and other patients also found it hard to follow conversations. This is because they missed lip movements and changing facial expressions, which are important parts of understanding what someone is saying. LM once said she felt unsafe when more than two people were walking in a room. She explained, "people were suddenly here or there but I have not seen them moving." Crossing the street and driving cars were also described as very difficult tasks for LM and others with motion blindness.

What Causes Motion Blindness?

Currently, three main things are known to cause motion blindness:

• Brain Damage: The most common cause is damage to the back part of the visual cortex in the brain. In LM's case, her brain was damaged on both sides in a symmetrical way.
• Temporary Simulation: Scientists can temporarily make healthy people experience motion blindness. They do this using a method called transcranial magnetic stimulation on a brain area known as V5, which is part of the visual cortex. This effect only lasts for a short time.
• Alzheimer's Disease: People who have Alzheimer's disease may also develop motion blindness. This can make their confusion even worse. While one case of Alzheimer's causing motion blindness has been studied, more research is needed on this connection.