This change in focus in an emergency is part of the "fight or flight" syndrome. It is only in part a brain phenomenon. Much of it is actually due to adrenal and pituitary gland secretions at the moment of threat. Actually, eye focus and peripheral vision changes [so you tunnel in on the threat and don't notice the surroundings]. Peripheral blood supply (to fingers and hands) stops and gets forced into the trunk of the body [so you can survive injuries to extremities better while protecting the core, and probably so you feel little pain at the time]. Blood pressure changes, respiration changes, and digestion ceases. Bladder and bowel evacuation in severe stress is actually a survival mechanism. After the crisis has passed, the nausea, trembling, sick feeling is probably as much a function of adrenalin "poisoning" or overload as it is of fear... which usually sets in many hours or days later.

Learning to modify one's "fight/flight" response syndrome is the critical element to psychological rehabilitation of Post Traumatic Stress Disorder victims, because they often essentially remain in the "fight/flight" mode and don't "reset". My bet is that the guy in the news story will have a startle reaction to anything brown/black and furry for some time!

Unfortunately, the visual tunneling can have a lethal effect on a law enforcement officer or soldier in a combat situation. I've worked with several who are so focused on the "perpetrator" and sight picture that they don't see the bad guys coming from the periphery. Good training actually teaches them to "break" the tunnel vision.