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The evolutionary origins of event cognition in hominids
Auteur(s)
Editeur(s)
Maison d'édition
Neuchâtel : Université de Neuchâtel
Date de parution
2024
Nombre de page
201
Résumé
How did syntax evolve in humans? Is there a direct transition from the simple forms observed in animal communication to the complex sentence structures seen in human languages? This thesis tested a new theory positing that human syntax is rooted in prelinguistic event cognition, an evolutionarily ancient propensity to decompose events into their causal components. Humans spontaneously attribute agents (doers of actions) and patients (undergoers) roles while viewing their interactions, i.e., “who does what to whom”, with a particular focus on agents. The current literature suggests that humans recognise agents faster than patients and dedicate more attention to them. Similarly in language, agents are typically placed before patients, are marked by simpler forms, and play a privileged role in language processing. But, how do animals understand the causal structure of events, how do they keep track of event roles, and in doing so, do they also experience a preference for the agent? This thesis aims to shed light on the evolution of event decomposition, as a putative precursor to human language and syntax, by comparing hominid species.
I first explored whether great apes, like humans, spontaneously encoded event roles. Using a switch cost paradigm (i.e., a reaction time experiment), I showed that switching the role (i.e., agent or patient) of the assigned target significantly increased the processing time of the participants. I then concluded that the propensity to spontaneously encode social events in terms of agents and patients is shared amongst hominids, and that it is impossible or very difficult to override this deeply anchored cognitive propensity. Secondly, I examined whether great apes also showed indications of agent preference. Using a non-linguistic task based on video clips that mimicked decision making during language processing, I found that all hominids had a robust preference for animate agents, especially when acting on objects. This preference transcended simple perceptual biases, again suggesting a shared propensity.
Building on these results I then tested for potential modulation of the agent preference by differences in cooperation levels. Results demonstrated that in both chimpanzees and humans, agent preference increased along the perceived cooperativity of the agent. Such results suggested that agent preference is affected by social factors, and similarly so in animals and humans. Finally, I focused on the computational abilities of hominids’ event perception. After watching video clips, participants selected the components of the events in serial order: the II agent, patient and action. Surprisingly, and in contrast to standard linguistic theory, all species, including humans, preferentially selected the action first, followed by the agent. The second preferred order was agent-action. I concluded that identifying the action was crucial for constructing the event structure, after which the agent preference became prominent.
Overall, these findings provide evidence that the ability to decompose events in terms of agent, patient and action evolved long before modern humans and, by extension, language. It implies that syntax-ready brains already existed for millions of years, dating back to at least the last common ancestor of hominids. What still remains unclear, however, is why the ability to externalise these structures with communication then evolved in humans and, correspondingly, why great apes, despite shared perceptual abilities, are prevented from sharing them with others.
I first explored whether great apes, like humans, spontaneously encoded event roles. Using a switch cost paradigm (i.e., a reaction time experiment), I showed that switching the role (i.e., agent or patient) of the assigned target significantly increased the processing time of the participants. I then concluded that the propensity to spontaneously encode social events in terms of agents and patients is shared amongst hominids, and that it is impossible or very difficult to override this deeply anchored cognitive propensity. Secondly, I examined whether great apes also showed indications of agent preference. Using a non-linguistic task based on video clips that mimicked decision making during language processing, I found that all hominids had a robust preference for animate agents, especially when acting on objects. This preference transcended simple perceptual biases, again suggesting a shared propensity.
Building on these results I then tested for potential modulation of the agent preference by differences in cooperation levels. Results demonstrated that in both chimpanzees and humans, agent preference increased along the perceived cooperativity of the agent. Such results suggested that agent preference is affected by social factors, and similarly so in animals and humans. Finally, I focused on the computational abilities of hominids’ event perception. After watching video clips, participants selected the components of the events in serial order: the II agent, patient and action. Surprisingly, and in contrast to standard linguistic theory, all species, including humans, preferentially selected the action first, followed by the agent. The second preferred order was agent-action. I concluded that identifying the action was crucial for constructing the event structure, after which the agent preference became prominent.
Overall, these findings provide evidence that the ability to decompose events in terms of agent, patient and action evolved long before modern humans and, by extension, language. It implies that syntax-ready brains already existed for millions of years, dating back to at least the last common ancestor of hominids. What still remains unclear, however, is why the ability to externalise these structures with communication then evolved in humans and, correspondingly, why great apes, despite shared perceptual abilities, are prevented from sharing them with others.
Notes
PhD thesis submitted to the Faculty of Science, Institute of Biology
Expert committee composition:
Thesis director – Prof. Klaus Zuberbühler, University of Neuchatel, Switzerland
Internal examiner – Prof. Adrian Bangerter, University of Neuchatel, Switzerland
External examiner – Prof. Michael Tomasello, University of Duke, United States
External examiner – Prof. Balthasar Bickel, University of Zurich, Switzerland
Defended on the 25th of September 2024
Expert committee composition:
Thesis director – Prof. Klaus Zuberbühler, University of Neuchatel, Switzerland
Internal examiner – Prof. Adrian Bangerter, University of Neuchatel, Switzerland
External examiner – Prof. Michael Tomasello, University of Duke, United States
External examiner – Prof. Balthasar Bickel, University of Zurich, Switzerland
Defended on the 25th of September 2024
Identifiants
Type de publication
doctoral thesis
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