In humans, watching a cat chase a mouse involves alternating attention between both animals, forming an agent-patient relationship - a process fundamental to human cognition and language development. To explore whether apes share this ability, researchers showed 84 video clips to 14 humans, five chimpanzees, two gorillas, two orangutans, and 29 six-month-old infants. The visual responses of apes and humans were then compared.

The results showed that adult humans and apes focused most on agents and patients, often alternating their attention between them. However, apes occasionally paid more attention to background details, especially in scenes involving food. In contrast, six-month-old infants concentrated primarily on the background, differing from both apes and adults. This suggests that the ability to break down events into agent-patient roles evolved before the emergence of language and is shared across species, forming part of a cognitive spectrum between humans and great apes.

The study emphasizes that this shared cognitive mechanism highlights a significant evolutionary link. The researchers noted, "Gaze patterns from eye tracking data suggest that apes, like human adults, can decompose causal actions into agent and patient roles, something that is crucial for language. Our findings are consistent with a shared cognitive mechanism between humans and apes, suggesting that event role tracking evolved long before language."

Further research is needed to understand why apes do not communicate in ways similar to humans and how language developed uniquely in humans.