Monkeys are curious about counterfactual outcomes

Area of Science:

• Cognitive Science
• Primatology
• Animal Behavior

Background:

• Non-human animals display exploratory behaviors, but human-like curiosity remains debated.
• Previous studies on animal information-seeking may be confounded by reinforcement processes.
• Defining and identifying curiosity in animals requires stringent, specific criteria.

Purpose of the Study:

• To investigate whether macaques exhibit human-like curiosity.
• To circumvent confounds in previous animal curiosity research by using counterfactual reasoning.
• To apply established criteria for curiosity to macaque behavior.

Main Methods:

• Macaques were presented with choices involving sacrificing fluid reward for information.
• The information provided related to counterfactual outcomes—what could have happened if a different choice was made.
• The amount of reward sacrificed was measured against the informational value (Shannon entropy) of the counterfactual option.

Main Results:

• Macaques demonstrated a willingness to sacrifice fluid reward to obtain information about counterfactual outcomes.
• The amount of reward macaques sacrificed systematically scaled with the amount of information available in the counterfactual option.
• This behavior aligns with criteria for curiosity, specifically the willingness to pay for information with no immediate instrumental benefit.

Conclusions:

• The findings demonstrate human-like curiosity in macaques, as defined by sacrificing reward for information with no immediate benefit.
• The study successfully used counterfactual reasoning to isolate curiosity from simple reinforcement learning.
• This research provides strong evidence for complex cognitive processes, including curiosity, in non-human primates.