Chimpanzees might be rational thinkers, capable of changing minds: Study

New Delhi, Oct 31 (PTI) Chimpanzees might be rational thinkers, capable of changing minds when presented with new information, a new study has found.

Findings published in the journal 'Science' challenge the traditional view that rationality -- the ability to form and revise beliefs based on the strength of available evidence -- is exclusive to humans, said researchers, including those from the University of California, Berkeley, in the US.

The team presented chimpanzees in the Ngamba Island Chimpanzee Sanctuary in Uganda with two boxes, one containing food.

The animals initially received a clue suggesting which box held the reward. They were later presented with stronger evidence that would point to the other box.

"Chimpanzees were able to revise their beliefs when better evidence became available. This kind of flexible reasoning is something we often associate with four-year-old children. It was exciting to show that chimps can do this too," author Emily Sanford, a postdoctoral researcher of psychology at the University of California, Berkeley, said.

The researchers analysed the observations through experiments and models to ensure that the findings reflected the chimps' genuine reasoning rather than instinct.

The analyses ruled out simpler explanations, such as the chimps favouring the latest signal, termed 'recency bias', or reacting to the most obvious cue, the researchers said.

The models showed that the chimps' decision-making aligned with rational strategies involving a revision of beliefs, they added.

"We recorded their first choice, then their second, and compared whether they revised their beliefs. We also used computational models to test how their choices matched up with various reasoning strategies," Sanford said.

Previous studies have shown that chimpanzees respond appropriately to evidence of varying types and strengths. However, beliefs can be formed based on evidence without explicitly reasoning out the evidence, the authors said.

"By contrast, the capacity to appropriately respond to counter-evidence and, especially, to second-order evidence -- evidence about the relevance of first-order evidence to one's belief -- is thought to constitute a key standard of reflective engagement with evidence," they said in the study.

The findings can help better understand the metacognitive capacities of animals, the researchers said.

Understanding how primates revise beliefs may also reshape how scientists think about learning, child development and even artificial intelligence, they added.

"Chimpanzees responded to counter-evidence in ways predicted by a formal model of rational belief revision: They remained committed to their initial belief when the evidence supporting the alternative belief was weaker, but they revised their initial belief when the supporting evidence was stronger," the authors wrote.

The findings "indicate that chimpanzees metacognitively evaluate conflicting pieces of evidence within a reflective process". PTI KRS KRS KSS KSS