Look Closely at This Footstep Illusion

The best optical illusions are the ones you can try at home. Take the footstep trick below: All you need to recreate it is a white sheet of paper with black stripes and a transparent film sheet marked with yellow and blue blocks. It may look simple, but move the film across the page and the colored shapes will appear to shuffle forward like tiny footsteps.

The illusion, recently shared by The Kid Should See This, is the creation of Akiyoshi Kitaoka, a professor with the psychology department at Kyoto’s Ritsumeikan University. He explained the mechanism at work in a paper he published with psychology professor Stuart Anstis in 2015 [PDF].

According to the report, the colored blocks need to be two times the width of the black stripe and either light (like the yellow ones) or dark (the blue ones) for the trick to pay off. The illusion is all about contrast, so the colors are essential. The authors explain:

“When the dark blue squares lie on white stripes, they have high contrast (dark vs. white) and they appear to speed up momentarily. When they lie on black stripes, they have low contrast (dark vs. black) and they appear to slow down. The opposite is true for the light yellow squares.

Consequently, the squares appear to go faster and slower in alternation, like a pair of walking feet.”

The brain takes all sorts of shortcuts when it comes to perceiving color, and most of the time this goes unnoticed. But when an artist knows how to exploit this it can lead to some mend-bending tricks, like this image from Akiyoshi Kitaoka in which three colors appear to be four. Check out more of Kitaoka's psychedelic illusions on his webpage.

[h/t The Kid Should See This]

Amazon's Under-the-Radar Coupon Page Features Deals on Home Goods, Electronics, and Groceries

Stock Catalog, Flickr // CC BY 2.0
Stock Catalog, Flickr // CC BY 2.0

This article contains affiliate links to products selected by our editors. Mental Floss may receive a commission for purchases made through these links.

Now that Prime Day is over, and with Black Friday and Cyber Monday still a few weeks away, online deals may seem harder to come by. And while it can be a hassle to scour the internet for promo codes, buy-one-get-one deals, and flash sales, Amazon actually has an extensive coupon page you might not know about that features deals to look through every day.

As pointed out by People, the coupon page breaks deals down by categories, like electronics, home & kitchen, and groceries (the coupons even work with SNAP benefits). Since most of the deals revolve around the essentials, it's easy to stock up on items like Cottonelle toilet paper, Tide Pods, Cascade dishwasher detergent, and a 50 pack of surgical masks whenever you're running low.

But the low prices don't just stop at necessities. If you’re looking for the best deal on headphones, all you have to do is go to the electronics coupon page and it will bring up a deal on these COWIN E7 PRO noise-canceling headphones, which are now $80, thanks to a $10 coupon you could have missed.

Alternatively, if you are looking for deals on specific brands, you can search for their coupons from the page. So if you've had your eye on the Homall S-Racer gaming chair, you’ll find there's currently a coupon that saves you 5 percent, thanks to a simple search.

To discover all the deals you have been missing out on, head over to the Amazon Coupons page.

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Jeff Koons's Puppy Sculpture, at the Guggenheim Museum Bilbao, Is Donning a Face Mask

Puppy by artist Jeff Koons is now sporting a face mask.
Puppy by artist Jeff Koons is now sporting a face mask.
Erika Ede/Guggenheim Museum Bilbao

Artist Jeff Koons’s Puppy sculpture located at the Guggenheim Museum Bilbao in Bilbao, Spain, has always been dynamic. The 40-foot-tall depiction of a West Highland Terrier is made of flower mantles that change with the seasons. From begonias and petunias in spring and summer to pansies in winter, it’s never exactly the same thing twice.

Now Koons is offering another variation on Puppy—a face mask made from flowers.

The addition was made in response to the COVID-19 pandemic that’s radically altered life for citizens worldwide and serves as a reminder that public health policy could save lives.

“What an honor it is to be able to have Puppy communicate the importance of wearing a mask during this time of the COVID-19 pandemic,” Koons said in a press release. “A Bilbao resident sent me a letter asking if Puppy could wear a mask, which I thought was wonderful idea. I was thrilled that the Museum agreed as now Puppy, adorned with a mask made of white and blue flowers, can communicate the importance of wearing a mask to protect against the spread of COVID-19.

"One of the most important acts that we can make to each other during this pandemic is to share information on how we can protect each other. I can imagine that the Puppy has appreciated all of the love shown toward it and is so happy to communicate safety and well-being to the citizens of Bilbao and the world.”

Puppy has been in residence since the Guggenheim Museum Bilbao opened in 1997. Koons has made a career of outsized sculptures. His Balloon Dog sold for $58.4 million in 2013.