Ever thought Mila Kunis looks like a squashed alien? Or that Angelina Jolie has hideously boggly eyes? Have you noticed Dame Judi Dench’s strangely box-like forehead?

Neither did we… until we watched this video.

On first glance it shows just a series of sickeningly beautiful and handsome celebrity visages. But look closely…focus on the cross in the middle of the screen and watch as these stunning mugs turn increasingly grotesque.

The phenomenon has been termed the “flashed face distortion effect” and was discovered by accident as a University of Queensland researcher idly flicked through a series of images.

SEE ALSO: Scary! Can You See The Spooky Faces In These Facebook Pictures?

On his website, Matthew Thompson describes how fellow undergraduate student Sean Murphy stumbled across the effect while working alone in a lab one evening.

He writes: “He (Sean) aligned a set of faces at the eyes and started to skim through them. After a few seconds, he noticed that some of the faces began to appear highly deformed and grotesque.

“He looked at the especially ugly faces individually, but each of them appeared normal or even attractive.”

As Io9 points out: “It’s not unlike viewing the world through a fun-house mirror that lives in your mind.”

In their paper published last year in the journal Perception, Thompson and Murphy, as well as Jason Tangen present their findings as “a useful tool for investigating contrastive distortion effects and face adaption.”

Below is a similar experiment by the same researchers, featuring non-celebrities. It was awarded second prize in the Best Illusion of the Year Contest, 2012.

And if you just can't get enough of the beautiful people looking rough as a bag of spanners, we've even included a gallery of celebs without their slap under the video. You're welcome.

Celebs Sans Slap

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• Stars Without Make-Up

  Pamela Anderson (Pic: WENN)

• Stars Without Make-Up

  Emma Watson (Pic: WENN)

• Stars Without Make-Up

  Jessica Alba (Pic: WENN)

• Stars Without Make-Up

  Myleene Klass (Pic: WENN)

• Stars Without Make-Up

  Kylie Minogue (Pic: WENN)

• Stars Without Make-Up

  Fearne Cotton (Pic: WENN)

• Stars Without Make-Up

  Amelia Lily (Pic: WENN)

• Stars Without Make-Up

  Marcia Cross (Pic: WENN)

• Stars Without Make-Up

  Eva Mendes (Pic: WENN)

• Stars Without Make-Up

  Edith Bowman (Pic: WENN)

• Stars Without Make-Up

  Helena Bonham Carter (Pic: WENN)

• Stars Without Make-Up

  Lesley Joseph (Pic: WENN)

• Stars Without Make-Up

  Carol McGiffin (Pic: WENN)

• Stars Without Make-Up

  Natalie Cassidy (Pic: WENN)

• Stars Without Make-Up

  Katy Perry (Pic: WENN)

• Stars Without Make-Up

  Vanessa White of The Saturdays (Pic: WENN)

• Stars Without Make-Up

  Beyonce (Pic: WENN)

• Stars Without Make-Up

  Kim Kardashian (Pic: WENN)

• Stars Without Make-Up

  Alexa Chung (Pic: WENN)

• Stars Without Make-Up

  Felicity Huffman (Pic: WENN)

• Stars Without Make-Up

  Gwyneth Paltrow (Pic: WENN)

• Stars Without Make-Up

  Mischa Barton (Pic: WENN)

• Stars Without Make-Up

  Sharon Osbourne (Pic: WENN)

• Stars Without Make-Up

  Madonna (Pic: WENN)

• Stars Without Make-Up

  Rihanna (Pic: WENN)

• Stars Without Make-Up

  Celine Dion (Pic: WENN)

• Stars Without Make-Up

  Kirsten Dunst (Pic: WENN)

• Stars Without Make-Up

  Kelly Brook (Pic: WENN)

• Stars Without Make-Up

  Kate Hudson (Pic: WENN)

• Stars Without Make-Up

  America Ferrera (Pic: WENN)

• Stars Without Make-Up

  Jessica Biel (Pic: WENN)

• Stars Without Make-Up

  Katie Holmes (Pic: WENN)

• Stars Without Make-Up

  Debra Messing (Pic: WENN)

• Stars Without Make-Up

  Jennifer Garner (Pic: WENN)

• Stars Without Make-Up

  Liza Minnelli (Pic: WENN)

• Stars Without Make-Up

  Claire Danes (Pic: WENN)

• Stars Without Make-Up

  Janice Dickinson (Pic: WENN)

• Stars Without Make-Up

  Whitney Port (Pic: WENN)