The difference waves were calculated for RC − congruent, SC − congruent and RC − SC. A repeated measures ANOVA was performed for group (3) × difference wave (3). A topographical analysis was also performed to further quantify the

differences between the three groups. Based on observations of the topographical differences between the three groups a series of electrode pools were used to capture this difference. The mean amplitude of the difference waves between 400 and 500 msec was examined at three central and parietal pools (central: 129, 31, 54, 55, 80, 79; left parietal: 58, 59, 65; right parietal: 91, 90, 96) (see Fig. 1B). A repeated measures ANOVA was performed for group (3) × congruency (3) × pool (3). The LRP was calculated according to convention (Coles, 1989): [(ER − EL) left hand response + (EL − ER) right hand response]/2. ER represents www.selleckchem.com/products/s-gsk1349572.html the amplitude of the ERP at the electrode over the right motor cortex, whereas EL represents the

amplitude of the ERP at the electrode over the left motor cortex. The left and right motor cortex electrodes were electrodes 36 and 104 respectively. These have the equivalent of positions C3 and C4 in the traditional 10–20 electrode system. The raw LRP waveforms were smoothed using a 50 msec moving average window to improve signal to noise ratio. The peak latency and peak amplitude of stimulus locked LRPs were calculated from 250 to 600 msec. Response locked LRPs’ peak amplitude, latency and mean amplitude were examined between −300 msec

and 0 msec relative to response. A repeated measures ANOVA of congruency (3) × group (3) was buy Lumacaftor done on the peak latencies and peak amplitudes. As the peak amplitude of the LRP can be variable particularly in developmental studies (Bryce et al., 2011) the mean amplitude of the LRP was also calculated with separate time periods for each group based on group differences in the mean RT data. In order to accurately detect the initiation of response selection the stimulus locked LRP peak latency was matched with Calpain the proportional change in RT in the three age groups. As the stimulus locked LRP tends to peak between 400 and 600 msec after stimulus onset young adults were examined between this time point. Adolescents RT was 45 msec faster than young adults therefore the LRP was examined 45 sec earlier than in young adults (355–555 msec). Middle age adults were 34 sec slower than young adults therefore the LRP was examined from 434 to 634 msec relative to stimulus onset. EEG data were processed using Brain Vision Analyzer (Brain Products, Munich), Matlab 7.9, SPSS 17.0 and Statistica 9. LRP jackknifing is a procedure commonly used in the LRP literature as it is thought to provide a more accurate estimate of LRP onset latencies (Lansbergen et al., 2007 and Miller et al., 1998; Wild-Wall, Falkenstein, & Hohnsbein, 2008).