Intuitive probabilistic inference in capuchin monkeys.

Area of Science:

• Cognitive Science
• Comparative Psychology
• Evolutionary Biology

Background:

• Probabilistic reasoning is crucial for survival in many species.
• Previous studies show infants and great apes can infer probabilities from population proportions.
• The evolutionary origins of probabilistic inference remain incompletely understood.

Purpose of the Study:

• To investigate probabilistic inference in capuchin monkeys (Sapajus spp.), a non-ape primate species.
• To explore the evolutionary roots of proportional reasoning.
• To extend previous research by including a novel experimental condition.

Main Methods:

• Nineteen capuchins were presented with two food item populations differing in preferred item proportions.
• Monkeys selected hidden samples drawn from these populations.
• Experiments included controls, replications of infant/ape studies, and a novel condition.

Main Results:

• Some capuchins successfully made probabilistic inferences using proportional reasoning.
• Performance varied, with poorer results in a novel condition, suggesting potential use of quantity heuristics.
• Performance was not optimal even in a non-probabilistic sampling task, indicating cognitive demands beyond proportion evaluation.

Conclusions:

• Capuchins possess the capacity for probabilistic inference through proportional reasoning.
• Cognitive demands of sampling tasks, including inhibitory control and working memory, influence performance.
• Further research is needed to fully elucidate the heuristics employed by capuchins in probabilistic decision-making.