A photographer tested the concentration of several pairs of dogs as he captured their reactions to treat time in a series of shots. Christian Vieler, 47, of Waltrop, Germany, has been a professional dog photographer since 2016. He came up with the idea of snapping two dogs catching treats simultaneously. Here: Basset Hounds. (Photo by Vieler Photography/Caters News Agency)

Cao Ri and Xu Jiaqian have a wedding photograph taken in a pool at the Qianyishi Underwater Photography Studio in Beijing, China on September 7, 2017. (Photo by Thomas Peter/Reuters)

Celebrities attend The National Reality TV Awards 2016 at the Porchester Hall in London, United Kingdom on September 29, 2016. (Photo by FameFlynet UK)

Danielle Sellers attends The Beauty Awards at Tower of London on November 28, 2017 in London, England. (Photo by Lia Toby/WENN)

English actress Kate Beckinsale attends the GQ Men of the Year Awards at Tate Modern on September 5, 2018 in London, England. (Photo by Karwai Tang/WireImage)

Taylor Swift attends the 2018 American Music Awards at Microsoft Theater on October 9, 2018 in Los Angeles, California. (Photo by Jon Kopaloff/FilmMagic)

Daniel Lismore arrives for the Brit Awards at the O2 Arena in London, Britain, February 20, 2019. (Photo by Peter Nicholls/Reuters)

Shortlisted: Sólheimasandur aircraft crash site, Iceland by Ollie Conway. (Photo by Ollie Conway/Historic Photographer of the Year Awards 2019/The Guardian)