Using eye tracking to study event cognition in great apes
To decompose the structure of an event requires one to identify the event protagonists (e.g. the boy and the girl) and the causal relationship between them (e.g. boy hits girl). Event decomposition is something that people automatically do when communicating about events, and is also evident in visual attention patterns when viewing events. That is, people tend to emphasise agents (the action doer) in syntactical structure, and exhibit visual bias towards agents over patients (the action recipient) in event scenarios. These findings suggest that event processing may be key to understanding the evolution of syntax found in language. To examine whether this agent/patient asymmetry is unique to humans, we have utilized eye tracking to compare how humans, chimpanzees, gorillas and orangutans view events. Specifically, we focus on how they attend to agent and patient roles within causal events, by presenting video scenarios of conspecifics and heterospecifics engaged in social interactions, or interactions with inanimate objects. Here, I present preliminary results from our first study. If agent/patient asymmetry is unique to language, we would expect to see differences between humans and other species in how they view agents and patients. If however agent/patient asymmetry occurs independently of language, we would expect to find attentional similarities between species. These findings should help us to understand semantic role attribution in an evolutionary context, and to determine the role of event decomposition in the evolution of hierarchical syntax.