Akinetopsia

Akinetopsia is a rare neuropsychological disorder, meaning it is a disorder between the nervous system and mental functions, in this case between the brain and perception. In this disorder the person affected by it cannot perceive motion.

Imagine the effects of a strobe light and how you do not seem to detect motion, but rather see a series of still images. However, there is more to akinetopsia than simply perceiving a series of changing, but static images without motion. Recall pictures of city lights taken while in a moving car at night. The lights have a sort of comet trail behind them. For people with this disorder, the comet trail of images is present as well. The movement of an arm can appear as several, fuzzy arms trailing after the original one. Only when they and the world around them is perfectly still do they see images normally. However, when things are moving there is a trail of repetitive images, such as one dog appearing several times in a trail after itself, which catch up to the original image when that object is standing still.

Causes
Akinetopsia is caused by a lesion in area V5 of the prestriate cortex. It can also be caused as a side effect of certain antidepressant drugs, or due to damage by a stroke or certain brain surgeries. In some cases akinetopsia can be treated by brain surgery or discontinuation of antidepressants.