FIGURE 5. The two-choice model of ant foraging decisions.

(A) Illustration of the decision model parameters. Noise Is omitted to better Illustrate the roles of the parameters γ and k (see Equation 2) in determining the ant’s decision in response to interactions. The bias rate γ sets the mean rate of change of the decision state in the absence of interactions, and k sets the increase in the decision state with each interaction. The initial decision state is set by the parameter s₀, and is set to zero for this example. (B) Example trajectories of the decision state with noise for the set of interaction times shown. Red lines: decision state s(t) of simulated ants that left the nest to forage. Blue lines: decision state s(t) of simulated ants that returned to the deeper nest. The decision time is shown by the dot at the end of each simulated decision path.