Here is how your brain might be trying to track all of that motion:

Eye to Brain:
South-east movement detected in location (+1^o,-3^o)
West movement detected in location (-2^o, -1^o)
North movement detected in location (-3^o, -2^o)
West-north-west movement detected in location (+1^o, +0.5^o)
....

Our images have as many as 400 points on them. There could be as many as 400 different “apparent motion” signals that the brain is trying to process, each with a distinct location, direction, and distance. That’s a lot of motion information for our brain to try to process!