Figure 2 . Topography of mean 15 Hz ssVEP activity averaged across stimuli in Habituation and Acquisition (A) and the corresponding FFT power at electrode Oz (B). The signal shows the involvement of the visual cortical areas at the driving frequency of 15 Hz.
SCR was filtered offline with a high cutoff of 1 Hz and the signal was segmented in epochs of -1000 ms to 8000 ms after stimulus onset. The signal was quantified using a manual Foot-to-Peak method with a latency time-window of 900 ms – 4000 ms after stimulus onset (Boucsein et al., 2012). We considered the first response peak following the foot located at 500 ms after the foot point until the end of the time window. Responses below 0.02 μS were scored as zero. Finally, SCRs were log transformed (log [1 + SCR]) to normalize the distribution and mean responses were calculated per condition and phase. We decided not to exclude non-learners based on SCR for two reasons: first, SCR is not a direct measure of learning and excluding participants solely on this can lead to sample bias (Lonsdorf et al., 2019). Second, since our experimental manipulation included different reinforcement schedules smaller SCR amplitude could be due to the experimental manipulation.