Researchers propose ‘ecologically honest’ approach to modelling behaviour
When studying the behaviour of species, study design is often based on human norms. But, when modelling the behaviour of non-human species, these biases can skew results. Now, one research team has proposed the adoption of "ecologically honest" design principles to better reflect the rythmic behaviours that are constrained by the physical form of any specific species being studied and account for their temporal differences.
“Failure of a non-human animal to synchronise in an experiment designed to test humans does not mean they are incapable of synchronising. It could also mean that the experiment was not appropriately designed to test a particular species,” said Koen de Reus of VUB’s Artificial Intelligence Lab and the Comparative Bioacoustics Group at Max Planck Institute for Psycholinguistics in the Netherlands.
VUB researcher Koen de Reus is part of an international team exploring the best way to study how animals synchronise behaviours such as moving, vocalising, and breathing. In humans and other animals, these rhythmic behaviours occur in various contexts: during mating, locomotion, and social coordination, for example. Study design is frequently based on human norms, but to effectively study synchronisation abilities in other animals, investigators need to consider a species’ temporal, physical, perceptual, and motivational constraints, which could be similar to or different than those of humans.
Image: A framework for mapping and considering rhythmic abilities across species. Line plots show preferred rates and empirical ranges for synchronization across a sampling of species
The research team is now proposing that a set of “ecologically honest” design principles, which is specific to the animal and the context, would give a better picture of its synchronisation abilities. In reviewing the literature, the researchers found that anticipation and tempo flexibility have previously been recognised as critical features of synchrony, but their opinion piece published in the Philosophical Transactions of the Royal Society B is the first to acknowledge that an animal’s tempo flexibility is restricted to a specific range. This means scientists must first establish the natural range of tempi at which animals produce rhythmic behaviours, in order to study whether they can synchronise.
According to de Reus, “All animals are temporally constrained by the physical limits of their bodies, their perceptual systems, and their behavioural ecology. The interaction of these three components determines a species’ degree of tempo flexibility. Although all animals that synchronise demonstrate tempo flexibility, the degree of flexibility varies across species. A range of tempo differences have been observed in the behaviours of different animals. Some have very flexible ranges, like humans and geladas, while others are more restricted, like bonobos and fiddler crabs.”
Motivation is key
The team also found that it is crucial to consider which behaviour a synchronisation task should test, as some behaviours are more easily synchronised to a stimulus than others. Researchers should therefore consider the modality (acoustic, visual, tactile) to which an animal synchronises best. For example, humans synchronise best to sounds, but this might not be the case for other animals. Finally, an animal’s motivation to perform a specific behaviour is highly context dependent. An individual behaviour may only become apparent when individuals form groups and studying this behaviour under controlled laboratory conditions would therefore require several individuals.
“An animal will perceive and can synchronise to a stimulus only within a species-specific range of tempi. However, this does not necessarily mean that if a stimulus falls within that range an animal will synchronise to it. It needs to be motivated to do so, and this is very much dependent on the situational context,” said de Reus.
To improve understanding of synchronisation abilities across the animal kingdom, knowledge from both laboratory experiments and field studies should be integrated. Lab settings allow researchers to control a range of variables that can test the full extent of a species’ ability to synchronise. Meanwhile, field studies can increase understanding of why, when, and how animal species synchronise in their natural environments. Observational data allow scientists to identify the behaviours a species can naturally produce, which can then inform controlled laboratory experiments.
Read the original paper, An ecological approach to measuring synchronization abilities across the animal kingdom published in Philosophical Transactions of the Royal Society B