Production of Supra-regular Spatial Sequences by Macaque Monkeys

Area of Science:

• Cognitive Science
• Primate Behavior
• Linguistics

Background:

• Human capacity for embedded sequences in language, music, and math is linked to supra-regular grammars.
• Supra-regular grammars generate complex embedded sequences beyond finite-state automata.
• The uniqueness of this human competence remains an open question.

Purpose of the Study:

• To investigate whether nonhuman primates possess the capacity for supra-regular grammars.
• To compare the learning of supra-regular grammars in macaques and human children.

Main Methods:

• A production task was used to train macaque monkeys on time-symmetrical embedded spatial sequences.
• The learned grammar's formal description required supra-regular grammars or push-down stack automata.
• Generalization to novel sequences and hierarchical embedding was assessed.
• Learning speed and strategy in preschool children were compared to monkeys.

Main Results:

• Macaque monkeys were trained to produce sequences describable by supra-regular grammars.
• Monkeys demonstrated spontaneous generalization to novel and longer sequences.
• Monkeys could generate hierarchical sequences with two levels of abstract rules.
• Preschool children learned the grammars significantly faster than monkeys, employing a chunking strategy.

Conclusions:

• Supra-regular grammars are accessible to nonhuman primates with extensive training.
• Human uniqueness may lie in the rapid acquisition and learning strategies for these grammars.
• This research sheds light on the evolutionary origins of complex cognitive abilities.