Dynamics in the system in a function of τ and σ (β ≡ 1, I1(t) = I2(t) ≡ 0.4).

Upper row: the neuronal dynamics r(t). Lower row: accumulated evidence p(t). A: no stimulus. The two populations have a constant firing rate, and the associated cumulative evidence is stable in time and equal to 50%, for both τ = 1.4[s] and τ = 1.7[s]. Since there is no stimulus, from the symmetry of the system, we have r1(t)≡r2(t). B: a weak stimulus (σ = 0.3[1/s]), for the subcritical value of τ = 1.4[s]. The system dynamics is still stable, and perceptual ambivalence does not occur. C: a weak stimulus (σ = 0.3[1/s]), for the supercritical value of τ = 1.7[s]. In this regime, accumulated evidence behind choices 1 and 2 fluctuates over time, which may account for perceptual switches. D: a strong stimulus (σ = 1.0[1/s]) for supercritical value of τ = 1.7[s]. The effect of ambiguity disappears, and the cumulative evidence for choice 1 is higher than the cumulative evidence for choice 2 for the whole duration of the experiment.