Mice are bamboozled by these baffling optical illusions... and so am I

An example of a neon colour spreading optical illusion that shows the appearance of what looks like a white circle on a background of black and blue lines.

We love a good optical illusion here at Creative Bloq. We even have a round up of the best optical illusions around. And after all the time we've spent trying to get our heads around them, it comes as some solace that mice are also fooled by such visual trickery.

Why wouldn't they be?, You may ask. But scientists are excited by the discovery because it could open up new ways to research perception.

In this example, it looks like there's a large blueish white circle in the centre of the image, but it's an optical illusion that results from neon colour spreading from the blue lines (Image credit: CC BY-SA 3.0)

The new research published in Nature specifically studied a type of optical illusion that involves what's called neon colour spreading. Falling into the category known as transparency effects, this kind of illusion is created by fluid borders between the edges of a colored object and the background when surrounded by black lines. Colour appears to spread from the coloured lines and create the illusion of an object that isn't there.

Here, a large blue circle appears in the centre of the image, but only the lines are blue. The background is the same white as in the surrounding portion of the image (Image credit: CC BY-SA 3.0)

The new research used an innovative combination of electrophysiology and optogenetics to explore how different levels of neurons process optical illusions in mice in order to settle a debate in neuroscience about which neurons in the brain are responsible for the perception of brightness.

After a visual stimulus reaches the eye, it’s taken to the brain by nerves and received by layers of neurons called V1, V2 etc. V1 is the first and most basic layer, and V2 and above are considered higher layers. By studying reactions to neon colour spreading optical illusions in mice, researchers found that V1 neurons respond to both illusory and non-illusory stimuli, while V2 neurons intensify the illusion by modulating V1 activity. This proves that that V2 neurons play a role in the perception of brightness.

Optical illusions shown to mice in the experiment. In the nine sets of white concentric circles, each contains gray segments at different positions. The gray color diffuses into the area between the circles, generating an illusory grating that appears darker than the black background (Image credit: Nature Communications / Alireza Saeedi, Kun Wang, Ghazaleh Nikpourian, Andreas Bartels, Nikos K. Logothetis, Nelson K. Totah & Masataka Watanabe )

The studies authors suggest the findings open new possibilities for using animal models to investigate neural mechanisms of perception and consciousness in cases where human studies can't be conducted.

For more visual trickery, see the new optical illusion that scientists can't explain.