Recursive sequence generation in monkeys, children, U.S. adults, and native Amazonians.

Area of Science:

• Cognitive Psychology
• Comparative Cognition
• Linguistics
• Anthropology
• Animal Behavior

Background:

• The unique computational capacities of humans, particularly nested hierarchical representations, are central to debates in cognitive science.
• The evolutionary, developmental, and cultural origins of these capacities remain controversial.
• Understanding these capacities is key to defining human cognition.

Purpose of the Study:

• To investigate the capacity for forming nested hierarchical representations in humans and nonhuman animals.
• To test for spontaneous generalization of sequential groupings to recursive structures.
• To explore the developmental and cross-cultural robustness of recursive thought.

Main Methods:

• A nonlinguistic sequence generation task was employed.
• Participants included children (3-5 years old), U.S. adults, and adults from a Bolivian indigenous group, alongside monkeys.
• Behavioral data were analyzed using a Bayesian mixture model to quantify cognitive strategies.

Main Results:

• Human participants (children and adults across cultures) spontaneously generated recursive structures from ambiguous training data.
• Monkeys required additional exposure to induce similar recursive structures.
• The Bayesian model confirmed the robust application of recursive hierarchical strategies in humans.

Conclusions:

• Recursive hierarchical strategies are a robust feature of human cognition, evident early in development and across diverse cultures.
• The capacity for forming recursive hierarchical representations is not exclusively human.
• This finding challenges previous hypotheses about uniquely human cognitive abilities.