The technical term for fuckin' tunnel vision is attentional narrowing. It's another prehistorically helpful but now potentially disastrous feature of the survival stress response. One focuses on the threat to the exclusion of almost everything else. Bruce Siddle tells a story about a doctor who had some fun with an anxious intern. He sent him across the emergency room to sew up a car crash victim's lacerations. The intern was so intent on his stitching that he failed to notice his patient was dead.