Plain-body octopus can be misled into believing false arms are their own
Kawashima and Yuzuku Ishima/Lucys University
Similar to humans, octopuses can be deceived by an illusion that leads them to believe that artificial arms are genuinely theirs.
This phenomenon, known as the rubber hand illusion, was first identified in the late 1990s, wherein a person’s hidden real hand is stroked alongside a fake hand placed before them. This trick was later found to impact other mammals, such as mice.
Recently, Kawashima and Samia, alongside Yuzuru Ikeda at the University of Ryukyu in Okinawa, Japan, discovered that octopuses are likewise susceptible to this illusion.
https://www.youtube.com/watch?v=f8ajppo0qyy
The experiment involved the plains of octopuses (Callistoctopus aspilosomatis) placed in a test tank. Soft gel fake arms, set atop an opaque partition, were placed over one of the octopus’s real arms, obscuring it from view. A researcher then stroked both the actual and fake arms simultaneously with a plastic caliper.
About eight seconds later, the researchers pinched the fake arm with tweezers. All six octopus subjects exhibited defensive behaviors, including color changes, arm retraction, and attempts to escape, across 24 trials.
The illusory effect diminished when the test was conducted without synchronized stroking, used non-synchronized stroking, or when the fake arm’s position didn’t align with the real arm.
During the experiment, the octopus could see false arms resting over a partition that obscured their actual arms
Kawashima and Yuzuku Ishima/Lucys University
According to Ikeda, the experiments reveal both advantages and disadvantages in the neural wiring of both octopuses and humans. “The illusion indicates an octopus’s ability to predict and anticipate, critical for survival,” he states. “Conversely, this capacity arises from neural conflicts and processing errors, suggesting a flaw.”
Kawashima asserts that this investigation will contribute to the understanding of octopus capabilities related to human experiences. “Our results imply that octopuses could serve as a vital model for studying the evolution of body ownership,” she mentions.
Peter Godfrey-Smith at the University of Sydney in Australia found the findings surprising. “This indicates that octopuses possess a complex body image,” he comments. “I was intrigued that the ‘positional mismatch’ scenario indeed worked—showing that the octopus didn’t perceive the rubber arm as its own in that specific situation.”
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Source: www.newscientist.com
