Figure 4.

Illustration of the time course of the posterior expectations at the third level of the Bayesian model (μ₃, top) and attentional gain allocated to the cued location α(π̂₁) (bottom), based upon the group average values for ω and ϑ. Because of the dependency of the galantamine-induced increase of ω, we here exemplarily show the results for a normalized weight of 68 kg (placebo session: ω = −6.2, ϑ = 0.60; galantamine session: ω = −5.4, ϑ = 0.61). It can be seen that, under galantamine (red line, with a higher ω), the changes in α(π̂₁) in the different true % CV conditions are more pronounced than under placebo (blue line). The same sequence of valid and invalid trials was presented each subject and in each experimental session because the parameters of the learning process depend on the exact sequence of trials used.