Research Reveals That Chimps Can Modify Choices Based on Evidence Similar to Humans
Chimpanzees have historically been viewed as intelligent beings, but their level of intelligence is still under investigation. A recent [study](https://www.science.org/doi/10.1126/science.adq5229) in *Science* examined whether chimpanzees possess metacognitive abilities. To assess this, the great apes undertook a sequence of five experiments with escalating complexity to evaluate their capacity to learn from errors.
The research took place in the [Ngamba Island Chimpanzee Sanctuary](https://ngambaisland.org/) in Uganda, where the chimps were provided with sensory input, specifically auditory, visual, and tactile signals. In each of the five experiments, the chimpanzees had the chance to decide which of two locations contained food.
In the first two experiments, chimpanzees made two selections based on strong versus weak evidence. Strong evidence was characterized by direct visual and auditory signals (for example, shaking a box filled with wood), while weak evidence involved indirect visual signals (like food traces outside the box) and auditory signals (shaking a box with peanuts).
The initial test indicated that when weak evidence was shown first, the chimpanzees opted for it. However, when strong evidence was introduced, they altered their choice. In the second trial, the initial presentation of strong evidence led the monkeys to select it and maintain their choice even after weak evidence was presented. This implies that after encountering both strong and weak evidence, chimpanzees can adjust their responses to achieve more precise outcomes.
The third experiment introduced a new box that lacked evidence relative to the existing weak and strong evidence boxes. Researchers then removed the strong evidence boxes to determine if chimpanzees would opt for the weak evidence or none at all. They predominantly selected the weak evidence (approximately 80% of the time) and received the reward.
In the fourth experiment, chimpanzees were asked to choose between redundant weak evidence they were familiar with (auditory shaking) or new weak evidence (auditory dropping). They demonstrated the ability to differentiate between various types of weak evidence, choosing the new evidence more frequently than the redundant one, which had previously proven untrustworthy.
The fifth and most intricate experiment yielded the most significant insights. Chimpanzees were provided with strong evidence followed by a new clue that could either function as a *defeater* or a *non-defeater*. This indicates that the new clue either contradicted the original evidence or had no effect. In the defeater condition, they were significantly more inclined to change their choice across both visual and auditory tasks, demonstrating their capacity to modify their decisions when their original evidence was compromised.
The findings revealed that chimpanzees can process evidence and make logical decisions based on both prior and current information, while also altering those decisions when necessary. This discovery illustrates that chimpanzees engage in rational thought, suggesting that metacognition is not solely a human quality. This insight could allow researchers to explore other primates and uncover the common ancestor capable of rational thinking and discern the point of divergence.
### A comprehensive, five-part study evaluated chimpanzees on their capacity for rational thought based on the evidence presented.
Photo: Warren Garst via [Wikimedia Commons](https://commons.wikimedia.org/wiki/File:Chimpanzee_with_offspring_in_tree_-_DPLA_-_05107647ac2b4431e3d6e044852163e2.jpg) (Public domain)
### Throughout the experiments, the great apes demonstrated their ability to evaluate different levels of evidence to make informed decisions and modify their selections.
Two young chimpanzees are engaging in play at Gombe National Park in Tanzania. (Photo: Cethuyghe via [Wikimedia Commons](https://commons.wikimedia.org/wiki/File:Chimps_in_Gombe.jpg), Public domain)
### The study concluded that chimpanzees possess metacognition similar to humans, which holds great significance for upcoming research aimed at enhancing understanding of both chimpanzees and humankind, as well as our evolutionary paths.
An alpha male chimp in Kibale National Park (Photo: Vincent Mugaba via [Wikimedia Commons](https://commons.wikimedia.org/wiki/File:An_alpha_male_chimp_in_Kibale.jpg), Public domain)
****Sources:** [Chimpanzees rationally revise their beliefs](https://www.science.org/doi/10.1126/science.adq5229), [Chimps Can Revise Their Beliefs When Shown New Evidence, Study Finds](https://www.sciencealert.com/chimps-can-revise-their-beliefs-when-shown-new-evidence-study-finds)*
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