Experiment 1: Sham tDCS over O1. Mean RTs are reported for the neutral condition (Fn, Hn), the congruent condition (Ff, Hh), and the incongruent condition (Fh, Hf). Error bars indicate SEM. Asterisks indicate significantly faster RTs in the congruent condition than in the neutral and incongruent conditions (all ps ≤ 0.04) and significantly slower RTs in the incongruent than in the neutral condition (p = 0.04).