Fig 3. Confirmation bias, conformism and the emergence of oscillations in vaccination coverage.

The emergence of oscillations (o) is depicted as a function of an infection’s reproductive rate (R₀) and the rate of negative side effects from vaccination (δ ^v). The emergence of oscillations is contingent on the inclusion of confirmation bias but not conformism and is observed for intermediate values of R₀. Three models are considered: Model 3 (without either confirmation bias or conformism); Model 4 (including confirmation bias) and Model 5 (including both confirmation bias and conformism). If no oscillations emerge, three dynamics can be noted for the distribution of opinions of vaccination: (i) coexistence of 2 opinions with a greater number of individuals with a positive opinion (+), (ii) coexistence of 2 opinions with a greater number of individuals with a negative opinion (-), (iii) all individuals have a positive opinion (*). The models are analysed for 2 different generation times (birth (b) = death (d) = 1 and 0.5) and for different values of the rate of negative side effects from infection (δ ^I). 1 million iterations were run with a time step of 0.0001 which correspond to 100 unit of time.