Common marmosets are sensitive to simple dependencies at variable distances in an artificial grammar

Area of Science:

• Cognitive Science
• Primate Behavior
• Bioacoustics

Background:

• Perceiving dependencies between elements in variable-length sequences is crucial for understanding language and music.
• This ability has been observed in chimpanzees, human infants, and squirrel monkeys, but its prevalence across primates is unknown.

Purpose of the Study:

• To investigate the capacity of common marmosets (Callithrix jacchus) to recognize and respond to auditory dependencies.
• To determine if this cognitive ability is widespread among primates.

Main Methods:

• A familiarization-discrimination playback experiment was conducted using pure tone sequences.
• Stimuli either conformed to or violated a grammatical rule, testing marmosets' ability to distinguish between consistent and inconsistent sequences.
• Marmosets' responses (looking time) were automatically recorded to avoid human bias.

Main Results:

• Marmosets spontaneously discriminated between sequences with and without dependencies, regardless of length.
• They looked longer at the sound source when presented with sequences consistent with familiarization stimuli.
• Automatic coding of behavioral responses ensured objectivity.

Conclusions:

• Common marmosets possess the ability to perceive auditory dependencies at variable distances.
• These findings support the hypothesis that this cognitive ability was present in the common ancestor of anthropoid primates (Simiiformes).
• The results contribute to understanding the evolutionary origins of complex auditory processing in primates.