Technology that can read the human mind sounds like the stuff of science fiction, but researchers in New Zealand say a technique they are testing gets pretty close.

Key points: 'Brain finger-printing' method can tell if a person knows certain information

'Brain finger-printing' method can tell if a person knows certain information Results have previously been accepted as evidence in US and Indian courts

Results have previously been accepted as evidence in US and Indian courts New Zealand scientists say more research is needed before more courts adopt it

Forensic brain wave analysis, or "brain finger-printing", is a method of analysing brain waves to see if a test subject has knowledge of certain information.

It was developed by American biological psychologist Lawrence Farwell in the 1980s but has failed to gain much traction as accepted evidence in courts.

The technique involves tracking the brain's involuntary responses to external stimuli, with the brain emitting an electrical pulse in response to information it has encountered before.

Christchurch-based University of Canterbury neuroscientist Richard Jones said after further testing the technique might be able to help solve crimes.

"The idea is that if you have committed a crime, then you've got something in your memory of the scene, or of a weapon, or whatever," he said.

"So if you and other suspects are tested later on by being shown some photos or words, your brainwaves react in a certain way to those stimuli."

Professor Jones said the technique has been admitted as evidence in a criminal case in the US state of Ohio, as well as in one case in India, but not yet in Australia or New Zealand.

"Dr Lawrence Farwell, who developed this, his claims of accuracy is that he's never faulted it," Professor Jones said.

"Of the 200 people he's seen and about 16 studies, it's never been faulted."

Professor Jones said it was still not clear if it was possible to defeat the tests by tricking the brain into forgetting or inventing memories.

"It is possible to inject fake memories, and we just don't know to what extent the brain finger-printing paradigm is quite robust relative to that."

Technique 'still a fair way to go'

But Professor Jones said more work needed to be done on the technique, and that he hoped his team's work in New Zealand would inspire other researchers to look into the method.

"There still needs to be more done in this space," he said.

Robin Palmer, who spearheaded the brain wave trial and works as director of clinical studies at the University of Canterbury law school, said the technology had a lot of potential.

But he admitted it could be a while before forensic brain wave analysis was admitted as evidence in Australian or New Zealand courts.

"From an admissibility to court situation, it's still a fair way to go," Professor Palmer said.

"If you go back to DNA, which was virtually discovered in 1953, the first time it was admitted in courts was 1988."

He said courts were reluctant to be first to admit new technology as acceptable expert evidence.

"Nobody wants to be first when it comes to scientific evidence, because you're putting your career on the line by making a decision which may turn out to be wrong or humiliating for you," Professor Palmer said.

The Christchurch trials will continue later in the year.