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)

A model has her hair done before The Blonds Spring/Summer 2016 collection during New York Fashion Week in New York September 16, 2015. (Photo by Carlo Allegri/Reuters)

A model backstagee is pictured before the Philipp Plein Spring/Summer 2016 collection during Milan Fashion Week in Italy September 23, 2015. (Photo by Alessandro Garofalo/Reuters)

A model waits to present a creation by Chinese designer Hu Sheguang for his collection show during China Fashion Week S/S 2016 in Beijing October 26, 2015. (Photo by Jason Lee/Reuters)

Fireworks explode around the London Eye wheel, the Big Ben clock tower and the Houses of Parliament to mark the beginning of the New Year in London, Britain, January 1, 2016. (Photo by Toby Melville/Reuters)

Men hang at the back of a truck loaded with farm produce along a road in Ikeja district in the commercial capital Lagos, Nigeria December 19, 2016. (Photo by Akintunde Akinleye/Reuters)

Pope Francis attends a circus performance during his weekly general audience at Paul VI hall on December 22, 2016 at the Vatican. (Photo by Alberto Pizzoli/AFP Photo)

A Chelsea Pensioner poses as he views displays through a floral design of Britain's Queen Elizabeth at the Chelsea Flower Show in London, Britain, May 23, 2016. (Photo by Toby Melville/Reuters)