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Many animals live in communities where individuals rely on each other for safety: herds of buffalo, murders of crows, schools of fish. Multiple pairs of eyes and other sensory organs are better at detecting a threat, and a reliable social alarm system can make the difference between life and death.
One longstanding assumption among behavioral ecologists has been that individuals in a network make decisions based on the average responses of their neighbors. So, for instance, a reef fish would flee to safety if enough of its neighbors showed signs of distress associated with an approaching predator.
But fleeing a foraging ground carries a cost, especially if the alarm turns out to be false. A fish might have a hard time finding its way back to a particularly desirable feeding spot, or forfeit the spot to a competitor. And while skipping dinner may not seem like a huge price to pay for possibly avoiding the jaws of a predator, for smaller bodied animals, including many species of birds and reef fish, failure to consume enough calories during the day can be life-threatening. Smaller animals have faster metabolisms than larger species and tend to have limited fat reserves, so they need to eat frequently to keep their bodies going. Fleeing also carries extra energy costs.
We were taken aback by how good fish are at ignoring misinformation.
“If you always follow your friends, you’ll keep running from non-existent threats, wasting energy and missing out on food,” says Ashkaan Fahimipour, a community ecologist from Florida Atlantic University.
When Fahimipour watched videos of reef fish going about life in their natural habitat, he realized they were actually quite selective about which social signals to heed. In some cases, anti-predator behaviors, such as darting, trigger a community-wide response, while in others, the shoal quickly chalks it up to a false alarm and ignores the signal.
“There’s a memory component in the circuit that acts sort of like a timer, waiting a bit to see if the [alarm] clears or if it gets stronger,” Fahimipour says. “This timer inhibits the alarm from going off immediately. In a way, this lets the system tune its own sensitivity.”
Fahimipour is the author of a new study that shows fish rely on a sophisticated decision-making circuit, where responses are adjusted according to the overall state of the network. The results of the analysis open the door for further insights into how information travels across animal social networks.
“Initially, we were a bit taken aback by how good these fish are at ignoring misinformation and quickly correcting when false alarms happen” Fahimipour says, “But after building a computational model and diving into the neuroscience of decision-making, it was more of an “of course” moment.” False alarms carry enough of a cost that it makes sense there is an adaptive mechanism that helps the fish filter out misinformation, he says. “Without that balance, their behavior would be a mess.”
Homo sapiens is not the only political animal.
Simon DeDeo, a cognitive scientist who studies complex systems at Carnegie Mellon University, believes the results support the idea that “Homo sapiens is not the only political animal.” Together with Elizabeth Hobson from the University of Tennessee, DeDeo has previously used studies of monk parakeets and pigtail macaques to demonstrate the point that, much like humans, animals rely on the other members of their social group to make decisions. “The idea is that every action exists within a social context” DeDeo says. “If you have a computer, and it gets a signal from the internet, there’s a protocol and that signal is interpreted the same way every time. But with these animals, the meaning of a signal is contingent upon other things that have happened previously.”
In DeDeo’s reading, Fahimipour’s reef fish follow the same score: They partly outsource decision-making to their network, which fluctuates between various states of sensitivity. “These animals understand that more information is not necessarily better,” DeDeo says. “There’s a sort of wisdom of the crowd.”
Fahimipour is particularly interested in how animals might respond to alarm overload—and how that might compare to human behavior. “One way animals seem to handle the issue of distinguishing between true and false alarms is by tuning down sensitivity to [their] neighbors and their actions when there’s too much information coming in,” he says.
Humans are a lot like the fish, he says. Bombarded with too much information? “It might be a good idea to take a step back and assess the situation for yourself.” 
Lead image: Abdallah A.elsharabasy / Shutterstock
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