One of the most endemic forms of social influence is persuasion. Persuasion, in contrast to many other sources of social influence, is an active process: somebody is, in a fairly conscious and planned way, aiming to change the opinions of somebody else. Cialdini also recognized the power of social influence on behaviour. Providing social proof for products involves demonstrating that people similar to a target of influence behave in the same way towards an object with the target to. The elaboration likelihood model argues that there are two distinct processing modes that come into play when people are being persuaded: the central processing route and the peripheral processing route. The heuristic systematic model also takes a dual-process approach to persuasion. It argues that people process information through two routes: systematic and heuristic. One emotion which is widely used in persuasion is fear. Fear generates both psychological and physiological arousal.