Fig. 3.

Svartdal (2008) schema of procedure. ITI inter-trial interval; S1/S2 stimulus 1/stimulus 2 (red, green lights varied per subject); $◊$ represents pause period; R1/R2 response 1 (produce opposite button press sequence to computer), response 2 (produce random sequence); $\mathit{\lambda }$ indicates the reward (correct choice feedback) with probability of receiving feedback given in brackets; $\mathit{\varphi }$ indicates no reward. One stimulus is presented at random per trial, one response is permissible per trial. Dashed lines are for ‘incorrect’ choice