Many animals have a good sense of smell, but can they smell chemical signals that indicate a person is fearful? In a horse study, published in 2023 in the journal Scientific Reports, researchers had participants watch clips from a comedy one day and a horror movie the next. After the participants watched each video, the researchers collected sweat samples using cotton pads and asked the participants to report how much joy or fear they felt while watching each clip. Then, the researchers presented the two swab samples from the same human to an assigned horse to see if it could discriminate between odors produced by humans during times of happiness and distress.