To rely on own experience or to do what others do? – testing conflict of information in the domestic pig
Eight test gilts, assigned to demonstrator gilts, were used to investigate whether pigs make foraging decisions based on their own experience or copy choices of conspecifics. Test gilts were trained to find food in one of four reward boxes where a blue rope was a cue indicating food location and, after learning, were subjected to two tests. Before each test, three correct choices was the success criterion for the tests to commence. In the Rope-Demonstrator (RD) test, test gilts watched a demonstrator enter and eat from a reward box while the rope indicated location of food in a different box. After removing the demonstrator, the test gilt could choose a box. In the Demonstrator (D) test the procedure was similar, but no rope was attached to any box. Test gilts were subjected to one RD test, four D tests and finally another RD test. In the first RD test, four pigs relied on their own experience, i.e. chose the box with the rope (Binomial distribution, p=0.0865), while two pigs chose the demonstrator box (p=0.311). In the second RD test significantly more pigs than would be expected by chance chose the box with the rope (p=0.00128). In none of the D tests did more test pigs than expected by chance choose the demonstrator box (p=0.311, p=0.311, p=0.058, p=0.311), but two individuals chose the demonstrator box significantly more often (p=0.0469). The test gilts had not previously experienced another pig in the arena, thus the novelty of the situation could have lead to a spontaneous random choice in the first test influencing choices made in the following tests. This experiment indicates that pigs rely less on their own experience when faced with a novel ambivalent foraging situation, and that some will copy the choice of a conspecific when their own information is lacking.