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)

Kyla Drumm, 5, waits after receiving the Pfizer-BioNTech coronavirus disease (COVID-19) vaccine in Skippack, Pennsylvania, U.S., November 3, 2021. (Photo by Hannah Beier/Reuters)

Russia's Kamila Valieva performs during the Exhibition Gala at the Rostelecom Cup 2021 ISU Grand Prix of Figure Skating in Sochi on November 28, 2021. (Photo by Dimitar Dilkoff/AFP Photo)

Prime Minister Theresa May meets Russian President Vladimir Putin during the G20 summit in Osaka, Japan on June 28, 2019. (Photo by Stefan Rousseau/PA Images via Getty Images)

José Pereira de Souza plays an accordion as actress and model Tatiana Melo gives a television interview in Feira Nordestina outside of the Olympic periphery on Wednesday, August 17, 2016. (Photo by Aaron Ontiveroz/The Denver Post)

A Brussels Airlines aircraft prepares for landing in Cointrin airport during sunrise over the Mont Blanc in Geneva December 1, 2011. (Photo by Denis Balibouse/Reuters)

India's Central Reserve Police Force personnel take part in a rehearsal for the Republic Day parade on a cold winter morning in New Delhi January 8, 2014. (Photo by Ahmad Masood/Reuters)

Local villagers fall onto the ground from an ox-cart as they ride to rid evil spirits from their village at Pring Ka-ek village, Cambodi. (Photo by Heng Sinith/AP Photo)