Octopuses and the Rubber Hand Illusion: New Research Reveals Body Ownership

Octopuses Exhibit body Ownership, Mimicking Mammalian Self-Consciousness

Amsterdam, Netherlands – July 28, 2025 – In a groundbreaking finding that challenges our understanding of consciousness, two Japanese researchers have demonstrated that octopuses, invertebrates with a vastly different evolutionary path from mammals, exhibit a sense of “body ownership.” This phenomenon, previously considered a hallmark of mammalian self-consciousness, was observed in experiments detailed in the latest issue of Current Biology.The research team, led by scientists from Japan, conducted a series of experiments with the octopus species Callistoctopus aspilosomatis.In a controlled tank environment,an octopus was presented with a fake rubber arm alongside one of its own tentacles,which was concealed by an opaque screen. When the researchers concurrently stroked the octopus’s real tentacle and manipulated the fake arm,the octopus displayed a distinct defensive reaction.This included changing color, retracting its actual tentacle, and attempting to escape – often exhibiting all these behaviors concurrently.

Crucially, when these stimuli were not synchronized, or when only the fake arm was touched, the octopuses showed minimal to no response. Similarly, when both the real and fake arms were visible simultaneously, the animals did not react. These findings suggest that the synchronized,yet distinct,tactile input is key to triggering the octopus’s sense of ownership over its body parts.

Biologists involved in the study conclude that octopuses possess a similar level of “ownership” regarding their bodies as mammals. This finding is particularly important given the known complexity of the octopus nervous system. Earlier this year, a study published in Nature Communications revealed that each of the hundreds of suction cups on an octopus arm possesses its own nerve center. With more nerve cells distributed throughout their arms than in their central brain, octopuses are often described as having “nine brains.”

While the precise connection between this distributed nervous system and the observed body ownership remains an area for further inquiry, the authors of the Current Biology paper suggest that the octopus’s unique neural architecture could offer novel insights into the development of body ownership across different species. The distinct evolutionary trajectory of the octopus nervous system, compared to that of mammals, may unlock new understandings of how self-awareness and bodily self-perception emerge.