attacking predators were often confused when the herd fled in all directions. Sometimes they literally stopped cold. Show a predator too many moving targets and it often chased none. The same thing was true of flocking birds and schooling fish—
That makes a lot of sense, actually. If each of the birds flew off so rapidly the swarm could only chase one, and it was trying to chase things as a group, then it would just freeze. No one target would be closer than the others, and without a complicated decision-making code(which we're repeatedly told the code must be kept small and simple to work) the swarms wouldn't be able to agree on a target to chase.
