CHILDREN literally see things differently when it comes to an optical illusion that sheds new light on the way human minds work, scientists say.
They enlisted Bendigo school students to discover more about how children perceive the world.
The scientists' findings have implications for people of all ages, as well as humanity's understanding of the strange paradoxes hiding in plain sight.
Researchers organised for children of different ages to look at an image containing the "Poggendorff illusion".
The image tricks the mind by superimposing a shape over a straight line. It makes the line appear disjointed.
The illusion has been causing artists and photographers headaches for centuries and has appeared - unintentionally or not, lead researcher and Bendigo-based academic Philippe Chouinard said.
"You see it particularly if you look carefully at Renaissance paintings because those artists were trying so hard to be as geometrically accurate and realistic as possible," he said.
"People would just draw a straight line and put an 'includer' [a technical term for an object or figure appearing in the illusion] over the top of it."
The Poggendorff illusion fools all humans to different degrees but some people think the line is more disjointed than others.
"What's very interesting is that the illusion's effects appear to be strongest in very young children. The effects diminish as they get older and reach adult levels by about 14-years-of-age," Dr Chouinard said.
The research zeroed in on the kind of mental capacity a child must develop for the illusion's impact to diminish.
Their findings suggested that change is to children's "higher level mental operations" rather than those used to sense the world around them.
Children's minds fully develop the capacity to sense the world around them earlier on and it is only as their language and puzzle-solving skills sharpen that Poggendorff illusion's effects weaken.
"Now that we've teased out that it is more about cognitive skills than sensory ones, the next step would be to hone in on what those particular cognitive skills are," Dr Chouinard said.
No-one completely understands why humans of any age are tricked by the Poggendorff illusion.
It could have something to do with the way our eyes turn our 3D world into a 2D image and sends it to the brain to be reprocessed.
Perhaps our minds are presenting us with what they deem to be the most likely 3D experience of the world, based both on what the eyes are telling us and our previous experiences of the world.
"Usually the brain gets this guesswork right. The Poggendorff is an example of where that might not be happening," Dr Chouinard said.
One theory suggests children might perceive the Poggendorff illusion differently to adults because their minds are not yet developed - their minds must overcompensate to make sense of the Poggendorff illusion.
It is hard to say for sure. It is extremely difficult to study the mind objectively.
For example, how does a scientist know that the person they are studying perceives the colour red the exact same way they do?
"I love this research because it demonstrates how two people's eyes can see the same thing very differently," Dr Chouinard said.
He said the latest research could help both push forward humanity's understanding of the mystery of the mind and potentially have implications for child psychology.
The research will appear in the June edition of the Journal of Experimental Child Psychologists.
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