Expectations when swimming in a group: The results of an experimental study suggest that fish can apparently also anticipate the behavior of group members in a similar way to athletes anticipating the movements of their fellow players and adapting to them. Guppies can therefore learn the typical movement pattern of an artificially controlled robotic fish in their group and then predict and adapt to its goal and movement pattern. The ability to anticipate could contribute to the fact that some fish species can coordinate themselves so surprisingly quickly in groups or shoals, the scientists say.
Man is particularly talented in “clairvoyance”: based on experience, we know what will most likely follow certain signs. When this serves to prepare for what is to be expected, it is called anticipation. This ability is particularly important when dealing with our fellow human beings: It is considered part of social competence that we can adapt to other people by anticipating adjustments to our own behavior. Among other things, the anticipation can also greatly increase our reaction speed when the behavior of others actually occurs.
"The basic ability to anticipate is innate in humans, but it can also be improved through training and practice," says lead author David Bierbach from the Leibniz Institute for Freshwater Ecology and Inland Fisheries (IGB) in Berlin. This becomes clear when anticipating in sports: "Studies have shown that professionals in ball sports are particularly good at using various indicators such as the posture or movements of their fellow players to predict what is about to happen," says the scientist.
Experiments with a fish robot
Studies have already shown that some animal species are also capable of anticipation in social contexts. However, it is not yet clear to what extent fish can predict the actions of their interaction partners and adapt to them. This question is particularly interesting against the background of the often pronounced synchronization behavior between fish in groups or schools. “Schools of fish often move very quickly and we already know some aspects that influence this. So far, however, it is unclear whether anticipation is part of this complex process," says Bierbach.
To shed light on this question, he and his colleagues have now conducted experiments with guppies. Although these well-known aquarium inhabitants are not particularly schooling fish, they do orient themselves to the movements of the members of their social group. As part of the study, the researchers examined whether the fish anticipate the movements of their neighbors in order to minimize the reaction time when the social partners change direction. A robot guppy was used that can be steered through the aquarium and performs movements that correspond to those of the natural models. Preliminary tests had shown that the fish reacted to the robot as if they were members of their community.
Forward-looking behavior is emerging
For the experiments, the scientists repeatedly let the artificial guppy swim the same zigzag route in the experimental tank, which always ended in the same corner of the aquarium. The real fish had the opportunity to learn both the position of the final target and the specific rotations of the artificial species. The scientists then recorded the reactions of the fish in the water tank in detail during the actions of the robot guppies.
As the researchers report, the evaluations of successive test runs reflected a clear trend in the movement behavior of the fish: They oriented themselves to the behavior of the robot and followed it to the corner of the tank. According to them, an anticipation behavior finally emerged: When the robot began to take its well-known zigzag route, the fish no longer just followed: Already in the third test run, more than half of all fish arrived at the target corner earlier than the robot fish . On the way there, too, the fish showed anticipatory behavior when following the robot, the team reports: they changed their turning behavior in response to the robot over the course of the experiments. Initially, the animals turned shortly after the corresponding movement of the robot - in the last experiment, however, they changed direction slightly in front of it.
“The results show that fish are able to anticipate the behavior of social partners and even get better at it with training. This could be another explanation for why fish in schools – which know each other well – are capable of extremely fast collective movements,” says Bierbach. The study results thus contribute again to knowledge about the often underestimated cognitive abilities of fish. In addition, research work of this kind could also have technical significance, the IGB emphasizes in conclusion: "Experiments like this can be important for understanding patterns of biological intelligence and for developing smart technologies".
Source: Leibniz Institute for Freshwater Ecology and Inland Fisheries, specialist article: Read Bioinspiration & Biomimetics, doi: 10.1088/1748-3190/ac8e3e