When you stub your toe or bang your head, why is the initial response always to yell "ouch" (or something less printable)? Scientists may have the answer. New research from the National University of Singapore suggests that vocalizing may interfere with pain signals traveling to the brain, distracting you from the uncomfortable sensations you're feeling. The researchers gathered 56 test participants and had each person submerge his or her hand into painfully cold water four separate times.