Electrophysiological evidence for different effects of working memory load on interference control in adolescents than adults

The present study investigated how the development of interference control is influenced by the development of working memory (WM) capacity during adolescence. In a dual-task, 17 adolescents (12–16 years) and 19 adults (18–48 years) performed a gender word–face Stroop task, while WM-capacity was manipulated by a concurrently performed N-back task. Behavior (reaction times, % errors and % misses) and event-related potentials associated with the detection (N450) of the Stroop conflict and response selection (sustained positivity; SP) were measured without or with a concurrent WM load. Adolescents had lower accuracy on N-back and Stroop trials than adults. N450 results showed Stroop conflict above temporal–occipital cortex which was suggested to be caused by processing of distracter faces. This N450 conflict response was smaller in adults and only present when holding a simultaneous WM-load, whereas adolescents' N450 conflict responses were already present without a concurrent WM-load and did not further increase with load. These N450 results indicate poorer distracter suppression in adolescence which is suggested to be due to insufficient attentional resources for top–down control. Irrespective of WM-load, adolescents also had larger parietal SP conflict responses than adults, suggesting inefficient response selection in case of activation of two conflicting responses. The main conclusion is that adolescents have worse distracter suppression than adults, caused by lower availability of resources for top–down control.

► In adults, the ability to control interference is related to working memory (WM) capacity.
► WM-load was manipulated while performing a Stroop task to study this relation in adolescence.
► Different ERP markers were used to study WM-load effects on conflict processing across time.
► Behavioral results showed that cognitive control functions are still immature in adolescents.
► ERPs showed higher distracter processing in adolescents already without a concurrent WM-load.