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)

Costumed participants are reflected in a woman's sunglasses during the Summer Carnival Street Parade, which travels through the streets of the center of Rotterdam, the Netherlands, 27 July 2019. Twenty floats participated in the parade with dance acts and lots of music. (Photo by Marco De Swart/EPA/EFE/Rex Features/Shutterstock)

A person wearing a face mask holds a cat on Swanston Street after cases of the coronavirus were confirmed in Melbourne, Victoria, Australia, January 29, 2020. (Photo by Andrew Kelly/Reuters)

Anna Malova, Miss Russia 1998, poses on a pool table at The Campbell Apartment restaurant in Grand Central Station on November 18, 1999. She makes her motion picture debut in the movie “Above Ground”. (Photo by Richard Corkery/NY Daily News Archive via Getty Images)

Zhang Shifan's sixth-generation facekinis in Shandong Province, Qingdao, East China. A woman credited with inventing the bizarre swimwear known as the “facekini” has now proudly presented the sixth generation of the iconic beach clothing. The new facekini models are not only more comfortable, they also come in a wider variety of colours and patterns, bringing both style and practicality to beach-goers in Qingdao City, in East China's Shandong Province, who fear tan lines. (Photo by CEN)

Smoke plumes rise from Mount Etna, one of the most active volcanoes in the world in Sicily, Italy on June 28, 2016. (Photo by Etna Walk/Rex Feature/Shutterstock)

A sanitation worker fumigates using sodium hypochlorite in an archive room to fight the spread of the coronavirus disease (COVID-19) in the Milimani commercial courts in Nairobi, Kenya, July 17, 2020. (Photo by Baz Ratner/Reuters)

A Viet Cong suspect holds his hands up after a Vietnamese Ranger from the 21st Vietnam Infantry Division routed him from his hiding place. (Photo by Keystone/Getty Images). 7th November 1967