The experiment was run on a personal computer (Pentium 4) with a QWERTY keyboard. Stimulus presentation, response registration and production of external triggers were controlled by E-Prime, version 1.1. A 17 in. monitor was placed in front of the participants at a distance of about 45 cm. EEG and electro-oculogram (EOG) were amplified with a Quick-Amp amplifier (72 channels, DC) and recorded with Brain Vision Recorder

(version 1.05) software. EEG was recorded from 61 Ag/AgCl ring electrodes located at standard electrode positions of the extended 10/20 system. An online average reference was employed. EOG was recorded bipolarly, both vertically from above and below the left eye and horizontally from the outer canthi of both eyes. Electrode impedance was kept below 5 kΩ. The EEG selleck chemicals llc and EOG data were sampled

at a rate of 500 Hz. Measured activity was digitally filtered online (low-pass 140 Hz, DC). For statistical analyses, Greenhouse–Geisser epsilon correction for the degrees of freedom was applied whenever appropriate. One participant was left out from the final analyses because of the large number of errors (61% correct keypresses, while all other participants had a percentage of correct keypresses of 85% or higher), which suggested that this participant did not fully comply Ruxolitinib chemical structure with the task instructions. Furthermore, EEG analyses were performed on all data without artifacts, because elimination of all trials with a single incorrect response would unnecessarily reduce the total number of EEG trials and might additionally introduce a bias for familiar vs.

unfamiliar sequences. The interval between the off-set of the last stimulus and the go/nogo signal was 1500 ms. The data was segmented starting 1600 ms before the go/nogo signal until 100 ms after the go/nogo signal. A baseline was set 1600–1500 ms before the go/nogo signal. The last stimulus remained present on the screen until the end of the baseline. Trials with artifacts (an amplitude difference larger than 100 μV Enzalutamide molecular weight within 50 ms) and out of range values (values larger than +/− 250 μV for prefrontal electrodes, +/− 200 μV for frontal electrodes, +/− 150 μV for central electrodes, and +/− 100 μV for parietal electrodes) were excluded from further analyses (comparable to Van der Lubbe, Neggers, Verleger, & Kenemans, 2006). Next, EEG was corrected for EOG artifacts by the Gratton, Coles, and Donchin (1983) procedure. Finally, a low-pass filter with a cut-off at 16 Hz was applied to average event-related brain potentials of individual participants. Response time (RT) was defined as the time between onset of the go-signal and depression of the first key and as the time between the onsets of two consecutive key presses within a sequence. The stimulus–response interval was always 0 ms. The first two trials of every block and after every break and trials with errors were excluded from RT analyses.