How we change what others think, feel, believe and do
Get somebody do something you want by suggesting that they do the opposite.
This works better when the other person is worked up and making emotional decisions rather than thinking things through.
A common form of reverse psychology is to forbid an action. When you say 'do not X' you are also implanting the suggestion to do X.
If they say they will do something, you can express doubt that they will do this. They then have to assert they will do it (and then actually do it) to prove you wrong.
If the other person is likely to believe you will use reverse psychology, you can go for a reverse-reverse effect by suggesting what you want them to do, but perhaps in an oblique and non-obvious way.
A father suggests that his rather stingy teenage son cannot afford to buy his sister a birthday present. The boy reacts by buying her a really nice present.
A student who is fed up with a friend who never helps says 'OK. Don't help. See if I care'. The friend reacts by helping.
A shy guy is provoked into asking a girl out when a friend suggests he is just not interested in girls.
Reactance theory says that people who feel their sense of control is being taken away from them will grab it back by not doing what they are asked. This can even be actions that are clearly against their best interests, for example as may occur in reaction formation.
Reverse psychology is more likely to be successful with people who have a high need for control. Rebellious teenagers who naturally do the opposite of what their parents say are classic targets, as are Type A people and those with narcissistic or even psychopathic tendencies.
Doing a reversal can also be used as a deliberate provocation to wake the other person up to their unreasonable stance. This requires them to think about what is said, which is quite different to the normal provocation of reactance which works best when they are in an emotional, unthinking state.
Where the other person may suspect reverse psychology is being used (which is typical of savvy teenagers), then reversing the reverse may be useful or perhaps using some form of cloaking to confuse the actual method being used. It can help if it seems that you do not care what decision they actually make.
There is a danger of reverse psychology backfiring, such as when the person realizes that you are trying to manipulate them and deliberately follows your suggestion as subtle revenge. Even if they believe you, they may also judge you as bad in some way for not making good decisions.
Another danger is that there is often more than one alternative to what you are suggesting and the person chooses just something else rather than the 'opposite' that you intend.
Rather than cause reactance, you can give indication that you are not forcing their decision, but still implant the suggestion in a self-reversing denial, for example by saying 'I'm not saying you should X'. The person now has to consider X but as they are not being asked to do it, they may now take it on board.