Fig. 1

The Stroop task paradigm. During the test phase, four kinds of trials were presented randomly against a black background: congruent (e.g., “RED” printed in red letters), incongruent (e.g., “GREEN” in blue letters), neutral (e.g., “ZHONG” in blue), and word identification trials (e.g., “YELLOW” in white letters). In the word identification trials, participants were instructed to press the key identifying the meaning of the word, whereas they responded to the color of the word in other kinds of trials