E tū union's Michael Wood has shared the moment he stopped a man attacking his girlfriend at a busy UK tube station.
The former Labour MP was appearing on AM alongside broadcaster Brodie Kane when they were asked whether their fight or flight mode would kick in when faced with situations like the Sydney mall stabbing.
Kane, who is a former lifeguard and served a four-year stint in the Territorials of the NZ Army, said people wouldn't know how they would react until under those circumstances.
"I, unfortunately, have run towards danger from time to time," Kane said.
"If someone was in trouble I am probably going to go straight to try and help."
Wood said he has had one experience where his fight-or-flight instincts kicked in. He was at a busy tube station in London with his wife about 15 years ago when a man had his girlfriend up against the wall and was "laying into her".
"It was fascinating to watch. You've got that bystander thing where everyone was just heads down, knew it was happening, but there was a natural human instinct to sometimes pretend it's not," the former Labour MP said.
"... I did go and approach the guy who just lost it."
He said it allowed the young women to "slip off" and he eventually talked him down.
"I don't think you ever know until you are in this situation. There's a whole lot of dynamics going on... We've had some of those situations here in New Zealand and sometimes you see incredibly brave people come forward."
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Newshub.