Evolution of heterogeneous perceptual limits and indifference in competitive foraging

The collective behaviour of animal and human groups emerges from the individual decisions and actions of their constituent members. Recent research has revealed many ways in which the behaviour of groups can be influenced by differences amongst their constituent individuals. The existence of individual differences that have implications for collective behaviour raises important questions. How are these differences generated and maintained? Are individual differences driven by exogenous factors, or are they a response to the social dilemmas these groups face? Here I consider the classic case of patch selection by foraging agents under conditions of social competition. I introduce a multilevel model wherein the perceptual sensitivities of agents evolve in response to their foraging success or failure over repeated patch selections. This model reveals a bifurcation in the population, creating a class of agents with no perceptual sensitivity. These agents exploit the social environment to avoid the costs of accurate perception, relying on other agents to make fitness rewards insensitive to the choice of foraging patch. This provides a individual-based evolutionary basis for models incorporating perceptual limits that have been proposed to explain observed deviations from the Ideal Free Distribution (IFD) in empirical studies, while showing that the common assumption in such models that agents share identical sensory limits is likely false. Further analysis of the model shows how agents develop perceptual strategic niches in response to environmental variability. The emergence of agents insensitive to reward differences also has implications for societal resource allocation problems, including the use of financial and prediction markets as mechanisms for aggregating collective wisdom.Author summary: Competition for resources is a major determinant of behaviour in both humans and other animals, as individuals seek resources that are both plentiful and under exploited by others. In order to identify these opportunities, individuals require high-quality information about the world, via their senses or by costly research into the options available to them. The price of conducting such research or maintaining the sophisticated sensory apparatus required is a drain on the foraging returns the individual can acquire, and thus there is a trade off between the benefits of effective foraging and the costs involved. In simple models of foraging behaviour, identical individuals that compete equally receive identical rewards regardless of where they choose to forage, since any advantage between choices is ultimately competed away. This presents an opportunity to make less effort in identifying the best foraging opportunities and avoid paying the associated costs. Here I show how this leads to the emergence of two distinct types of behavioural types: informed agents that continue to assess the value of different options, and uninformed agents who choose at random. Investigating further, I show how informed agents further diversify according to the variety of options they are likely to encounter.