Figure 7.

Search efficiency of colonies measured as total number of items collected after 10⁴ time steps (with a time step equal to 0.2 s, the time between frames in the experimental data), averaged over 100 realizations as a function of p and for different values of the stack size S which were 1 (squares), 5 (circles), 20 (triangles) and 100 (inverted triangles). For panels (a,c), ants are considered either as risk-prone or risk-averse and p represents the fraction of risk-prone individuals, while for panels (b) or (d) all individuals can exhibit both personalities, p in this case being the overall fraction of risk-prone excursions. Panels (a,b) correspond to (β = 0.1), while (c,d) correspond to β = 0.5. The values of the other parameters used in the model are L = 1, γ = 0.01, α = 0.5, k = 5 and ω = 0.01.