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Fish tune out social cues to avoid false alarms 

A new study led by Cornell University has found that fish can adjust their sensitivity to the actions of their conspecifics – such as fleeing due to a false alarm – in order to reduce the risk of responding to misinformation, a decision-making mechanism that is shared by other animals, including humans.

When wild coral reef fish swim alone or in small groups, they pay continuous attention to the behaviors of other fish and they tend to imitate them. For instance, when fish nearby startle, they are more likely to flee themselves. 

However, in larger and more dense fish schools, where individuals are more likely to startle or flee for no reason, fish often tune down their sensitivity to social cues. While such behavior does not necessarily discriminate between true threats and misinformation, it nevertheless lowers the probability of responding to false alarms.

By using new computer vision tools, machine learning, and computational modeling, the scientists analyzed the behavior of foraging coral reef fish in Mo’orea, French Polynesia. The analysis revealed that, when there is a lot of visual motion around them, causing some fish to be edgy or skittish even in the absence of concrete threats such as predators, many fish seem to lower their sensitivity to the actions of their conspecifics in order to avoid behaviors triggered by false alarms.

“When we looked at the features of the model that matched observed behavior, we found that it adjusts the sensitivity of individuals to signals produced by others, based on the past history of what they’ve been seeing,” explained lead author Andrew Hein, an assistant professor of Computational Biology at Cornell. “Mechanisms for adjusting sensitivity are actually crucial if you’re going to maintain control over your behavior.”

Although more research is needed to clarify how and why such adjustment strategies evolved, these findings suggest that the evolution of how brains process information could have been driven by the need to cope with misinformation.

“Because of its simplicity, and the ease with which it can be implemented in the nervous system, we believe this form of dynamic control of sensitivity may be widespread in biological systems and may have evolved as a simple but robust way of coping with misinformation,” Hein concluded.

The study is published in the journal Proceedings of the National Academy of Sciences.

By Andrei Ionescu, Staff Writer

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