STUDY: Tiny fish passed intelligence test that once distinguished great apes
A 2018 study reported that the ‘cleaner wrasse’ had passed the mirror mark test, but evolutionary psychologist Gordon Gallup believed the fish in these experiments were mistaking the marks on their own bodies for parasites on other fish. In this study, the fish were marked first, then the mirror was introduced for the first time. The fish were likely aware of something unusual on their body, but they couldn’t see it. When the mirror appeared, it immediately provided visual information that matched an existing bodily expectation, hence scraping occurred much faster. This implies self-awareness before being exposed to the mirror.
SCIENCE ALERT: A tiny fish has shown signs of a remarkable level of intelligence in mirror test experiments, not only recognizing itself in the reflection but also using a piece of food to explore how the mirror works.
Mirror mark tests are a standard scientific experiment used to explore animal self-recognition, gauging how similar other species’ intelligence might be to our own.
Fixing your smudged eyeliner on seeing your reflection is a clear sign of self-recognition. You know the smudge on your face is out-of-place, and you can use the reflection as a proxy for pinpointing exactly where to wipe the smudge away.
In theory, a reaction to an out-of-place mark in a reflection is assumed to be evidence of self-recognition for other animals as well. Chimpanzees, elephants, and dolphins are just some that have passed this mark test, which many regard as a sign of intelligence similar to our own.
The cleaner wrasse (Labroides dimidiatus) is a finger-sized marine fish that earned its name by eating the parasites and dead tissue it finds on other, larger fish. It was first reported to pass the mirror test in 2018…
Though the 2018 study reported that the fish had passed, the mirror mark test’s founder, evolutionary psychologist Gordon Gallup, told New Scientist he believed the fish in these experiments were mistaking the marks on their own bodies for parasites on other fish.
Now, a team from Osaka Metropolitan University in Japan and the University of Neuchâtel in Switzerland has tweaked the experiment to test the wrasse’s self-awareness even further…
“In earlier cleaner wrasse mirror studies, the procedure was typically the fish see a mirror for several days, they habituate to it and stop reacting socially, and a mark is added,” animal behavioralist Shumpei Sogawa from Osaka Metropolitan University in Japan explains.
“In this study, the order was reversed; the fish were marked first, then the mirror was introduced for the first time. The fish were likely aware of something unusual on their body, but they couldn’t see it. When the mirror appeared, it immediately provided visual information that matched an existing bodily expectation, hence scraping occurred much faster”…
The scientists were surprised by how fast the fish reacted in these new experiments: on average, they tried to rub off the ‘parasite’ within about 82 minutes. This, they say, implies self-awareness before being exposed to the mirror. JESS COCKERILL
RELATED VIDEO: