## Shape up! Tricky optical illusion challenges puzzlers to find all of the triangles in the image – so, how many can YOU see?

• Tricky optical illusion was shared on the website for US-based Optics4Kids
• Offers no clues to challengers on how many of the shapes are present in the snap
• At first glance, seems to show two triangles – one facing up and one upside down

A fiendishly tricky optical illusion challenging people to find all of the triangles in the image is the latest puzzle driving the internet to distraction.

The drawing – which was shared on the website for US-based Optics4Kids – is a Kanizsa Triangle, and offers no clues as to how many of the shapes are present in the picture.

At first glance, the sketch seems to capture just two triangles – one facing up and another turned upside down.

A fiendishly tricky optical illusion challenging people to find all the triangles in the image (pictured above) is the latest puzzle driving the internet to distraction

However, the website’s answer reads: ‘There are no triangles. In reality there are only 3 V shapes and 3 shapes that look like Pac-Men.’

The Kanizsa Triangle demonstrates how the brain can be fooled into seeing things that aren’t really there.

In the illusion, a white triangle can be seen in the image even though there is no such shape present.

At first glance, the sketch seems to capture two triangles – one facing up and another turned upside down. However, the website’s answer reads (above): ‘There are no triangles. In reality there are only 3 V shapes and 3 shapes that look like Pac-Men.’

The impression is caused by the brain’s tendency to see objects which are grouped together as part of a whole – a theory known as the Gestalt effect.

Because humans tend to ignore gaps and perceive contour lines to connect nearby shapes, we convince ourselves the lines we are looking at make up a triangle.

It’s the latest in a long stream of optical illusions to have baffled the internet, after a 3D arrow that can never point west similarly left social media users puzzled.

The simple-looking arrow points east no matter which way you turn it, thanks to a clever – and frustrating – optical illusion.

It’s the latest in a long stream of optical illusions to have baffled the internet, after a 3D arrow that can never point west left social media users puzzled The simple white arrow, perched on a wooden stand, points east

The trickery begins when a finger is seen turning the arrow 180 degrees…

However, when the arrow reaches the 180-degree mark, it appears to still be pointing right

The deceptive arrow is the handiwork of Japanese sculptor and mathematician Kokichi Sugihara and relies on gentle curves on the arrow’s surface to mislead the brain.

Millions have now watched the video of the arrow being turned 180 degrees, and its point still facing east, with many saying the clip ‘messed with their head’.

A finger is seen gently moving the pointer, which sits on a wooden stand, around from right to left. However, even after the swivel, the arrow appears to still be facing east.

Original poster @thamkhaimeng explained: ‘This arrow by mathematician and sculptor Kokichi Sugihara can’t point left. Here’s how it works: It’s 3D-printed with a bunch of curves our brains don’t register.’

The trick to the optical illusion is explained when you look directly down on the arrow, when the contours of the arrow are more clearly visible. When looked at from a certain angle, the brain can’t compute those curves.