Under pressure in the Eriksen flanker task.

Abstract

A classical observation in experimental psychology is a reduction in reaction time and response accuracy under time pressure (TP). This speed-accuracy tradeoff may be understood from the combined perspectives of affordance competition and urgency gating. This view implies that action programs compete with each other from stimulus onset until the final response. Furthermore, responses are thought to be determined not just by the outcome of this competition but also by the urgency to respond. The latter aspect may play an important role in the case of speed stress. An experiment was conducted employing the Eriksen flanker task with different levels of TP. Behavioral, electromyographic (EMG), and electroencephalographic (EEG) data were registered. In the EEG analysis, source-level time-frequency activity was isolated for three sources (occipito-temporal, motor, and medial-frontal cortex). Inter-source phase coherence was computed to assess the neural dynamics underlying the effects of TP and flanker congruency. The EEG and EMG data revealed that TP affects visuo-motor links and motoric processes, while the flanker congruency effect was present from a very early level up to the final response. The present findings fit well within the combined perspectives of affordance competition and urgency gating.