Therefore, in middle age adults the increased negative amplitude of the right scalp shift of the N450 in the RC condition could represent intermediary level of processing, more than young adults but less than older adults, required for response conflict resolution. By using a combined ERP and EMG methodology we have tracked in real-time the course

of stimulus and response conflict processing during the Stroop task. Our study confirms previous findings that both stimulus and response conflict contribute to the Stroop effect (slower RT during incongruent trials) (Chen et al., 2011 and Houwer, 2003). However by using CB-839 price multiple response related measures we have delineated important markers of the Stroop effect at the response level of processing. The current findings support the idea that Stroop conflict, during this manual colour word Stroop task, may be more robust at the response level of processing. In this study we found that there were no differences in the behavioural and neural processing of the two types of conflict (SC compared to RC) when examining accuracy, P3a, P3b and N450 activity. However the LRP peak latency was significantly later in the RC condition than the SC condition and the EMG activity

in the correct responding hand was significantly less in the RC when compared to the SC condition, indicating stronger correct check details responses during SC. This perhaps indicates that during this manual colour word Stroop task the Stroop effect may be more robust during the period of processing between response selection and response execution. Interestingly this occurred across all age groups. We predicted that adolescents would

show increased response conflict, for example in poorer behavioural performance during RC and differences in neural activity during RC. We also predicted that middle age adults would show increased stimulus conflict, in terms of increased resources and poorer behavioural performance during the SC condition. Although we found age-related differences in information BCKDHA processing stages, the conflict manipulations in this task were not sensitive to age differences. Perhaps this task did not evoke age differences because the conflict conditions were of a similar level of difficulty. Indeed, the similar neural markers (P3a, P3b, N450) and accuracy performance in the SC and RC conditions indicate that these conditions were not very different in terms of level of difficulty. This could explain why we could not detect any age differences in the task manipulations. This warrants further examination. We combined ERP and EMG to examine lifespan changes in stimulus and response conflict processing using a modified Stroop task. Asymmetries in conflict processing across the lifespan were determined.