Researchers have discovered chimpanzees can revise their beliefs when presented with new evidence. This is an ability that was once thought exclusive to humans, but these findings suggest it may be much more widespread across species.
In a new paper published in Science, researchers tested a group of chimpanzees by providing either a strong or weak piece of evidence to suggest whether or not a box contained food, such as by shaking it to make a sound, or directly showing them what was inside.
They would then repeat this with a second box by providing a new piece of evidence that was either stronger or weaker than the initial piece.
When the new piece of evidence was stronger than the original, the chimpanzees would change their mind and begin indicating the new box, but when it was weaker, they ignored it and continued to indicate the initial box, which suggests that they were updating their beliefs in line with the evidence.
Further experiments showed even more sophistication from the chimpanzees. As before, the researchers offered a clue about one of the boxes, but then revealed it to be misleading. For example, they would show that one of the boxes contained food, but then pull out a piece of paper to show that the “food” that they had seen was merely a picture.
When a previously strong piece of evidence was defeated this way, the chimpanzees would discard it and look to the next strongest piece of evidence.
You can read the full paper here