Psychology: Social Influence

Why are emotional appeals effective in some advertising campaigns while they're not in others? How do we encourage people not to cycle in pedestrian areas? How to study the effectiveness of measures to prevent tax evasion? Many organisations and companies benefit from effectively influencing the behaviour of citizens or consumers. There are public health agencies trying to encourage people to exercise regularly, whereas advertising agencies try to increase sales of a particular product and municipalities try to discourage littering in parks. But how can we develop a strategy that is effective in achieving these goals?