It's easier for people to forgive someone for doing wrong against them if some form of punishment is involved, according to a new study.

Psychology researchers at the University of Adelaide found that people were more willing to forgive if those who had offended against them had been punished in some way.

The study included a range of different scenarios involving someone who has done wrong - a negligent friend; a criminal offender; and a troubled personal relationship.

"Justice and forgiveness are often considered to be opposites, but we've found that victims who punish their offender are more able to forgive and move on," said Dr Peter Strelan at the University of Adelaide's School of Psychology.

"Punishment could take many different forms. It could be giving someone the 'silent treatment', which in itself is a very powerful psychological punishment.

"Or in the case of a criminal offender, knowing that a court of law has imposed a reasonable sentence and that justice is being done - that may be enough for some people to forgive.

"That sense of justice, or getting 'just deserts', is important. However, in interpersonal relationships punishment should not be extreme or vengeful - if it were, this would not help to repair the damage in the relationship and is likely to make things worse.

"For forgiveness to really work, there must be a sense that negative responses towards a transgressor are being replaced with positive ones.

"It's not about retaliation, it's about responding constructively and doing something about people's poor behaviour toward you, in a way that works for both parties involved in the conflict," Strelan said.

Strelan said many people have a difficult time forgiving those who have done them wrong.

"When you get hurt by someone you naturally feel vulnerable, and the very idea of forgiving someone also makes a victim feel vulnerable. When some form of punishment is involved, the victim feels more empowered by that and is more able to forgive," he said.