When a child reading a sentence comes across a word they don't know, their eyes either linger on it or quickly move on to the next word.
"They either sound out c-a-t or they just move on," said Professor Anne Castles, who is leading a Macquarie University program that uses brain-imaging technology to map how children learn to read.
Conversely, it's brighter children who are more likely to speed along through sentences because they are better at memorising words.
But these students tend to suffer down the track, according to UK Schools Minister Nick Gibb, who has overseen the administration of phonics tests to year 1 students that Australia is set to adopt.
"These children memorise stories and think they can read and they go on for a long time before teachers realise they actually can't," Mr Gibb said.
"They could be eight or nine by that time."
Mr Gibb is in Australia to compare education systems and joined NSW Department of Education secretary, Mark Scott, and Education Minister Rob Stokes at a public event on Tuesday night to discuss policy.
Professor Castles pointed to the technology used by the university's Centre of Excellence in Cognition and its Disorders and her research in the area over the past decade as evidence in favour of a phonics check, which forms part of a suite of education reforms that are being considered by the Turnbull government.
"When a child first comes to school, they have thousands of spoken words," Professor Castles said.
"What they have to learn is how to crack the code, how to match letters to the words they know.
"If you don't have phonics, learning to read is like learning the telephone book. You can only learn so many words."
Professor Castles said introducing phonics testing in schools would force teachers across the country to adopt the technique, improving the reading success of all schools.
"We'll see the effects of it quite quickly," she said.
Education research fellow at the Centre for Independent Studies, Jennifer Buckingham, who is a leading advocate of phonics, said the verdict on the reading technique was in and classrooms need to catch up.
"Why is there this persistent disconnect between extremely valuable research and classroom practice?" she said.
"It's a little thing, but one that's really important in learning to read."
Ms Buckingham is part of a panel of six principals, teachers and academics who will make recommendations to the government around the implementation of national reading, phonics and numeracy checks for year 1 students by the end of the month.
The phonics check aims to identify struggling students early and will be based on the UK model of a five-seven minute test in which students are asked to read aloud 40 real and made-up words.
However, the checks have proven controversial among teachers, with the NSW Teachers Federation describing it as "anti-teacher".
President of the Australian Education Union Correna Haythorpe said: "Schools already have assessment processes in place for students when they start school to determine who needs extra support with literacy.
"An extra test is not necessary and will not make a difference to a child's learning without the extra resources to help students who are behind."
Education Minister Simon Birmingham earlier this year said billions of dollars in federal education funding would be tied to the implementation of the reforms.
The move towards the new checks follows Australia's stagnating results in NAPLAN reading, writing and numeracy tests and declining performance in the Program for International Student Assessment (PISA).