Most popular sports are both spectator and participant, for example association football, basketball, cricket, tennis, rugby, golf, athletics and volleyball.Spectator sports have built their own set of culture and traditions including, in the United States, cheerleading, team mascots, and pre-game and half time entertainment such as fireworks, particularly for big games such as competition decider events and international tests.The passion of some sports fans also means that there are occasionally spectator incidents.The North American Society for Sport Management (NASSM) devotes much of their annual conference to research addressing the psychology behind a desire to view spectator sports, and how it might be leveraged to increase demand.Much of the research focuses on exploiting a need for vicarious achievement, and a desire within the spectator to project a public image through a declaration of team allegiance.