The evolution and social cost of herding mentality promote cooperation

Abstract

Herding behavior has a social cost for individuals not following the herd, influencing human decision-making. This work proposes including a social cost derived from herding mentality into the payoffs of pairwise game interactions. We introduce a co-evolutionary asymmetric model with four individual strategies (cooperation vs. defection and herding vs. non-herding) to understand the co-emergence of herding behavior and cooperation. Computational experiments show how including herding costs promotes cooperation by increasing the parameter space under which cooperation persists. Results demonstrate a synergistic relationship between the emergence of cooperation and herding mentality: the highest cooperation is achieved when the herding mentality also achieves its highest level. Finally, we study different herding social costs and its relationship to cooperation and herding evolution. This study points to new social mechanisms, related to conformity-driven imitation behavior, that help to understand how and why cooperation prevails in human groups.

Keywords: Psychological evolution; Psychology; Sociology.

Graphical abstract

Figure 1

Cooperation levels in generalized pairwise game on S and T Left plot shows cooperation for a regular lattice and right plot for SF network under different values of S and T.

Figure 2

Final levels of cooperation in a lattice and SF when introducing herding costs Left and right plots show, respectively, the absolute cooperation levels and increase in cooperation with respect to the generalized pairwise game for an SA on S and T when including herding costs in the game. Top plots are for SF network and bottom plots for regular lattice. An important increase in cooperation for the SF is observed. When in a regular lattice, there is an area where we can see an increase of cooperation but also a slighter decrease below the diagonal of the plot.

Figure 3

Evolution of strategies and payoffs over time Left plots show evolution of frequency of strategies and right plots do for their averaged payoffs in the four strategies co-evolutionary game (first row) and generalized pairwise game (second row). Settings are $S=-1,T=0$ on an SF network for $\mathrm{3,000}$ steps. The introduction of the herding strategy rapidly moves the population to full cooperation until the end of the simulation as both $HC$ and $\tilde{H}C$ payoffs are higher than those of $HD$ and $\tilde{H}D$.

Figure 4

Increase in herding and cooperation levels for lattice and SF Increase in final frequency of players adopting herding and cooperation with respect to the baseline generalized pairwise game for an SA on S and T. The first row is obtained in a regular lattice and the second row is in an SF network.

Figure 5

Social weight impact on co-evolutionary herding and cooperation levels Sensitivity analysis on social weight τ for the herding behavior for three pairs of S and T: $\left(-\mathrm{0.4,0.9}\right)$, $\left(\mathrm{0,2}\right)$ and $\left(-\mathrm{0.1,1}\right)$. The model includes the co-evolution of herding mentality and cooperation (SF network setting).

Figure 6

Increase in herding social costs boosts cooperation Rows of heatmaps when running an SA on $\left(S,T\right)$ and increasing the values of τ ($\left\{\mathrm{0.5,1,1.5,2.5}\right\}$) in an SF setting. We plot the final number of herders ($\tilde{H}C+\tilde{H}D$) in the first column and final number of cooperators ($HC+\tilde{H}C$) in the second column. Higher social weight values increase cooperation for the whole map of values of the pairwise game.).