Effect of group size on producer-scrounger strategies of Wistar rats

Visual social information use in collective foraging

Collective dynamics emerge from individual-level decisions, yet we still poorly understand the link between individual-level decision-making processes and collective outcomes in realistic physical systems. Using collective foraging to study the key trade-off between personal and social information use, we present a mechanistic, spatially-explicit agent-based model that combines individual-level evidence accumulation of personal and (visual) social cues with particle-based movement. Under idealized conditions without physical constraints, our mechanistic framework reproduces findings from established probabilistic models, but explains how individual-level decision processes generate collective outcomes in a bottom-up way. In clustered environments, groups performed best if agents reacted strongly to social information, while in uniform environments, individualistic search was most beneficial. Incorporating different real-world physical and perceptual constraints profoundly shaped collective performance, and could even buffer maladaptive herding by facilitating self-organized exploration. Our study uncovers the mechanisms linking individual cognition to collective outcomes in human and animal foraging and paves the way for decentralized robotic applications.

To produce or not to produce? Contrasting the effect of substance abuse in social decision-making situations

Substance use disorders (SUD) have been related to high criminal justice costs, expensive healthcare, social impairment, and decision-making deficits. In non-social decision-making tasks, people with SUD tend to take more risks and choose small immediate rewards than controls. However, few studies have explored how people with SUD behave in social decision-making situations where the resources and profits depend directly on participants' real-time interaction, i.e., social foraging situations. To fulfill this gap, we developed a real-time interaction task to (a) compare the proportion of producers (individuals who tend to search for food sources) and scroungers (individuals who tend to steal or join previously discovered food sources) among participants with SUD and controls with respect to the optimal behavior predicted by the Rate Maximization Model, and (b) explore the relationship between social foraging strategies, prosocial behavior, and impulsivity. Here participants with SUD (n = 20) and a non-user control group (n = 20) were exposed to the Guaymas Foraging task (GFT), the Social Discounting task (SD), and the Delay Discounting task (DD). We found that participants in the control group tended to produce more and obtain higher profits in contrast to substance abuser groups. Additionally, SD and DD rates were higher for scroungers than producers regardless of the group. Our results suggest that producers tend to be more altruistic and less impulsive than scroungers. Knowing more about social strategies and producers' characteristics could help develop substance abuse prevention programs.

Social Determinants of Inter-Individual Variability and Vulnerability: The Role of Dopamine

Individuals differ in their traits and preferences, which shape their interactions, their prospects for survival and their susceptibility to diseases. These correlations are well documented, yet the neurophysiological mechanisms underlying the emergence of distinct personalities and their relation to vulnerability to diseases are poorly understood. Social ties, in particular, are thought to be major modulators of personality traits and psychiatric vulnerability, yet the majority of neuroscience studies are performed on rodents in socially impoverished conditions. Rodent micro-society paradigms are therefore key experimental paradigms to understand how social life generates diversity by shaping individual traits. Dopamine circuitry is implicated at the interface between social life experiences, the expression of essential traits, and the emergence of pathologies, thus proving a possible mechanism to link these three concepts at a neuromodulatory level. Evaluating inter-individual variability in automated social testing environments shows great promise for improving our understanding of the link between social life, personality, and precision psychiatry – as well as elucidating the underlying neurophysiological mechanisms.

Can the setup of a patch modulate finder's advantage?

According to the Rate Maximization Model the finder's advantage is an environmental factor modulating social foraging strategies. One factor that can influence the finder's advantage is the patches' setup. We analyzed the strategies of Wistar rats foraging in groups n = 4 in a 4 × 3 array of deposits where only four of them were baited (patches) with different configurations on each trial. Specifically, the goal was to assess whether the finder's advantage varied according to the distribution (Square vs. Zig-zag) and distance (Small vs. Large) between patches. Foraging responses were classified as production (seeking for food) or scrounging (tracking conspecifics) to calculate the frequency of use of each strategy in each group and estimate the induced finder's advantage in each situation. In patch-setups with short distances, production was more common and the finder's advantage higher. Results can be explained by the combined effect of a local enhancing and simultaneous patch exploitation on small setups.