This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Tropical army ants are known to form devastating armadas that march through forests eating other insects and small creatures. As they march, they deposit chemical trails of pheromones that others behind them sense and follow.
But occasionally one of these ants will walk in a circle, prompting a subset of ants behind them to follow until they all collapse and die. "They end up in this cycle where they're reinforcing the same pattern over and over again," said Andrew Hein, associate professor of computational biology in the College of Agriculture and Life Sciences. "This is a physical instance of an echo chamber, where the animals involved actually die." Hein is senior author of a new study that examines how a few general constraints can lead to echo chambers—self-reinforcing feedback loops—in groups of biological agents such as birds in a flock, cells in tissue or ants in a swarm, and explores ways to control them.
The paper, published Sept. 22 in the Proceedings of the National Academy of Sciences, uses mathematical models to test parameters that increase and decrease the likelihood of an echo chamber forming. In humans, the phenomenon occurs in groups when individuals send and receive similar messages and lack external sources of differing information. Many biological systems in which individuals collectively make decisions—such as fish in a school darting away from a suspected predator—face two key constraints, according to the paper.
First, an individual often observes only a neighbor's discrete actions and doesn't know all the internal information that led that neighbor to behave in a certain way. Second, individuals have limited attention at any moment and can attend to the actions of only a few neighbors, rather than many of them at once. The study reveals that these constraints can make individuals extremely sensitive to messages they receive from others and encourage them to send and receive similar messages back and forth, creating an echo chamber.
"It happens when people are telling each other the same thing, but there's also an implication that this group has become unresponsive to what's actually happening in the world around them," Hein said. In the study, Hein and colleagues started with computer models previously studied by other researchers in which agents in a network shared the actual data that caused them to form a particular opinion or take a particular action. "It's as if I express my opinion to you, but instead of telling you what my opinion is, I tell you everything that I ever learned that caused me to form that opinion," Hein said.
The model also assumed that any agent in the network could pay attention to all of its neighbors at once. With these two assumptions in place, the models did not form echo chambers. "One of the reasons why we found these assumptions interesting is that they appear to be violated in every system we could think of," Hein said, meaning individuals rarely have all the information that led to an action or opinion, nor can they pay attention to many things at once.
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