Abstract
Street fight videos on the internet may provide information about little known aspects of human physical aggression, but their reliability is unclear. Analyses of 100 dyadic fight videos addressing ethological, game theoretic and sex-differentiated questions derived from research on other animals found that prefight verbalizations or gestural signals of nonaggressive or aggressive intent loosely predicted who would strike first and who would win. The head is the preferred strike target. Ordinal severity rankings of different strikes ranged from 1 for spitting to 5 for choking. Half the videos showed briefer, unilateral assaults beginning with one or more high severity strikes, little evidence of escalation and fewer bystander interventions. A quarter of these were sneak attacks. The other videos showed longer fights with reciprocal strikes, some evidence of strike severity escalation and more bystander intervention. Both types were equally injurious. Winner/loser outcomes were reliably identified by postfight behaviors and/or signs of injury. Winners had advantageous prefight resource holding potential (RHP: greater height and/or vigor) significantly more often than losers. Consistent with tendencies for fights to occur between animals of the same sex, there were more male/male and female/female fights and fewer male/female fights than expected from random pairings of men and women in the videos. Female/female fights involved proportionally more hair-pulling, extended bouts of rapidly repeated strikes and longest durations. Bystanders intervened in over half the videos, attempting to separate fighters or help losers more often than they attacked the loser. Carefully selected internet street fight videos can provide important information.