Recursive sequence generation in crows.

Area of Science:

• Cognitive Science
• Animal Behavior
• Evolutionary Psychology

Background:

• Recursion, the embedding of structures within similar structures, is often seen as a cornerstone of human symbolic competence.
• Understanding the evolution of recursion involves studying recursive aptitudes in nonhuman animals.
• Previous research has shown that humans and nonhuman primates possess recursive abilities.

Purpose of the Study:

• To investigate the presence and extent of recursive capacities in crows.
• To compare crow recursive abilities with those of humans and other primates.
• To explore the evolutionary origins of recursion beyond the primate lineage.

Main Methods:

• Crows were presented with sequences of bracket pair stimuli (e.g., [ ] and { }) in a training task.
• A behavioral protocol, similar to studies on humans and primates, was adopted.
• Crows were tested on their ability to transfer center-embedded structures to novel bracket pairings.

Main Results:

• Crows exhibited significant recursive capacities, performing comparably to human children.
• Crows outperformed macaques in tasks assessing the understanding of center-embedded structures.
• The crows maintained recursive sequence production even with increased embedding depth.

Conclusions:

• Recursive capabilities are not confined to the primate lineage.
• The findings suggest recursion may have evolved independently or earlier than human symbolic competence.
• Crows possess sophisticated cognitive abilities that include understanding complex hierarchical structures.