Auditory artificial grammar learning in macaque and marmoset monkeys.
Benjamin Wilson1, Heather Slater, Yukiko Kikuchi
1Institute of Neuroscience, and Centre for Behaviour and Evolution, Newcastle University, Newcastle upon Tyne, NE2 4HH, United Kingdom, Department of Psychology, University of Cambridge, Cambridge, CB2 3EB, United Kingdom, and School of Philosophy, Psychology and Language Sciences, University of Edinburgh, Edinburgh, EH8 9AD, United Kingdom.
Summary
Monkeys can learn artificial grammars, but Rhesus macaques show deeper structure-learning abilities than common marmosets. This suggests Old World monkeys possess more complex artificial grammar learning (AGL) than New World monkeys.
Area of Science:
- Cognitive Science
- Comparative Psychology
- Neuroscience
Background:
- Artificial grammars (AG) model language structure, and AG learning (AGL) assesses nonhuman animal structure-learning capabilities.
- Comparing AGL across species is challenging due to varied AG structures.
- A quantitative parameter space was developed to summarize nonhuman AGL results.
Purpose of the Study:
- To investigate artificial grammar learning (AGL) in two monkey species using a forward-branching auditory AG.
- To compare the AGL complexity between New World monkeys (marmosets) and Old World monkeys (macaques).
- To explore the potential of these species as neurobiological models for AGL.
Main Methods:
- Habituation of common marmosets and Rhesus macaques to an auditory artificial grammar.
- Analysis of video recordings to assess sequence discrimination.
- Utilizing a novel eye-tracking approach to confirm and quantify AGL in macaques.
Main Results:
- Common marmosets differentiated grammatical sequences but relied on simpler strategies.
- Rhesus macaques demonstrated evidence of deeper, more complex AGL.
- Eye-tracking confirmed advanced AGL in macaques, suggesting higher complexity in Old World monkeys compared to New World monkeys.
Conclusions:
- Rhesus macaques exhibit a higher level of artificial grammar learning complexity than common marmosets.
- This study reveals a previously unrecognized difference in AGL capabilities between Old World and New World monkeys.
- Marmosets and macaques can serve as valuable neurobiological models for studying AGL at the neuronal level.
