An Australian-led study into jury bias has found the way defendants are positioned in court could be playing on jurors' prejudices.

More than 400 mock jurors have taken part in a controlled experiment to test whether they were more likely to deliver a guilty verdict if the defendant were sitting in an enclosed glass dock, in an open dock or at the bar table with their lawyer.

The lead researchers ran the three scenarios during a fake terrorism trial at a high-security court in western Sydney earlier this year.

"People think they can detect their own prejudices," David Tait from the University of Western Sydney told Lateline.

"In fact all the psychology evidence is they can't and you need to do a randomised controlled trial to see how people actually behave as opposed to how they think they behave."

The jurors were presented with the same witnesses and same evidence based on the real terrorism trial involving nine Sydney men, including the now notorious Khaled Sharrouf and Mohammed Elomar.

The study has found 60 per cent of jurors delivered a guilty verdict when the defendant was in the glass dock, 47 per cent for the traditional open dock and 36 per cent for the US-style bar table.

Mr Tait said the jurors were also asked what they thought of the defendant in the three different positions.

"The impressions were that the accused was more dangerous, more violent and more threatening in the glass box," he said.

In Australia, glass enclosures were used initially in two high profile terrorism cases in Melbourne and Sydney but were eventually removed because of concerns it would prejudice the juries.

Glass docks should only be used in extreme cases: judge

Former Supreme Court judge Anthony Whealy presided over the Sydney trial and said glass docks should not be used except in extreme cases.

"The judge's task is to make sure someone gets a fair trial," he said.

An actor sits in a glass dock in a staged trial for the University of Western Sydney study into jury bias. ( Supplied: Filigree Films )

"And that involves eliminating or reducing prejudice and bias wherever it's possible."

Mr Tait said the results show the glass dock undermines the presumption of innocence.

"They are more likely to lead to conviction and they fundamentally undermine the right to a fair trial," he said.

The researchers point to the trial of journalist Peter Greste, where he and other defendants appeared in a metal cage in a Cairo court, as an extreme example of how perceptions can be skewed.

The full results of the study will be presented at a legal conference in Melbourne on Friday.