The pig has been shown to use mirrors to find food. In a classic experiment, pigs learned that a mirror could reveal the location of a food bowl hidden behind a barrier, demonstrating that they could use reflected information to understand their surroundings.
In the 2009 study by Donald Broom, Hilana Sena, and Michael Moynihan, seven of eight pigs that had several hours of mirror experience located the concealed food. Pigs without that experience often searched behind the mirror itself, treating the reflection as though it were a real opening or object. This distinction showed that the animals were learning what a mirror represents, not merely reacting to a shiny surface.
The finding is often confused with passing the mirror mark test. Pigs can use mirrors for spatial information and show mirror-directed behaviors, but they have not been reliably shown to pass the classical mark test for visual self-recognition. Their strong smell, memory, and problem-solving abilities also make them capable of finding food in many ways without mirrors.