Don't think - just jump straight in

Rhys Humphries (left) and Maurice Doyle pulled a man from a burning car in the US last month.

People who risk their lives to save others "act first and think later", new research shows.

But an Auckland University psychology expert says whether a good Samaritan acts is more likely to be because of the level of emergency, and the number of other people around.

It follows a series of dramatic rescues by Kiwis both in New Zealand and overseas in recent weeks, including a selfless act by Auckland mother-of-six Lucy Knight, badly injured trying to stop a mugging, and that of Hamilton man Tumanako Pairama who bravely fought off a dog mauling its owner to save the woman's life.

The American research, by David Rand from Yale University, examined the statements of civilian heroes who risked their lives to save strangers and found jumping in to help was an intuitive response.

"We wondered if people who act with extreme altruism do so without thinking, or if conscious self-control is needed to override negative emotions like fear," Dr Rand said.

"Our analyses show that overwhelmingly, extreme altruists report acting first and thinking later."

But Dr Danny Osborne, a social psychology lecturer at Auckland University, said whether a person's involvement in an emergency was intuitive or controlled was still up for debate.

Dr Osborne said it came down to the situation and how many other people were around.

The more people there were at an emergency, the less likely people were to help.

"If you get hurt on Queen St and there's 100 people walking by, you're much less likely to be given assistance than if you're on Albert St and there's five people walking by."

It also made a difference if the situation was a clear emergency. For example, a person trapped in a car submerged in a river was clearly an emergency, compared with someone who couldn't be seen having a heart attack in a car parked on the side of the road.

For New Plymouth man Maurice Doyle, both schools of thought proved to be true.

Mr Doyle was travelling through the Nevada desert with friend Rhys Humphries, 45, when the pair came across a crashed car late last month.

The 58-year-old said the pensioner trapped in the burning car could not get out by himself.

"He was in need of help. I didn't really think about it."

When asked why he risked his own life, Mr Doyle said he had no choice.

"We were the only ones there. There was no one else to help."

The husband of Lucy Knight, Peter Thomas, previously said he was not surprised his wife intervened in a mugging because she had a strong sense of justice.

And Hamilton man Tumanako Pairama didn't believe he was a hero for jumping the fence of Michelle Lovett's Nawton home last month and beating off her attacking mastiff with a broom handle.

Instead, Mr Pairama said he considered himself a person "helping another person in need".

Of the 51 medal-winning good Samaritans studied, 82 per cent were men.

Auckland University lecturer in criminology Dr Ronald Kramer said perhaps it was not about altruism but about men being socialised to play some kind of heroic role.

He said it was not surprising that people recounted their act of bravery as an intuitive response.