Fig. 3: Changes in behavioural policy are modulated by the richness of the environment.

a Example sequence of trials and operationalisation of policy-related variables. Behaviour was characterised along two dimensions: (1) a policy dimension reflecting option-specific decisions to pursue-vs-reject the three available reward-options, and (2) an action dimension reflecting non-option-specific decisions to pursue-vs-reject an option regardless of the reward option available. Trials were then categorised as (i) policy-stay events if the pursue-vs-reject decision was consistent with the previous encounter, or (ii) policy-switch events if the pursue-vs-reject decision was different from the previous encounter. Similarly, trials were categorised as (i) action-stay if the pursue-vs-reject decision was the same as the preceding trial (regardless of reward option), and (ii) action-switch if the pursue-vs-reject decision changed. b Pursue-rates as a function of (i) previous action and (ii) previous policy. Bars indicate sample-mean pursuit-rate; dots indicate participant-level pursuit-rates. c Policy-switches frequency as a function of reward-option. Bars indicate the mean count of policy-switches per experimental session at the sample-level; dots indicate participant-specific counts. d Switch-rate for pursue-switches and reject-switches as a function of environment type. Data shown for the 10-point option only. Bars indicate sample-level mean switch-rate, dots indicate participant-level switch-rate. e Probability of (i) pursue-switches and (ii) reject-switches as a function of the average value of recent reward-options. Data shown for the 10-point option only. Lines and shadings indicate the regression line ± SEM. Points and error bars indicate mean ± SEM switch-rates in decile bins of average value. In all panels, n = 27; *p < 0.05, **p < 0.01, ***p < 0.001 two-tailed.