Figure 1.

Task description. For each task, a stimulus consisted of one letter and one digit. The task to be performed was indicated by the color of the stimulus. For example, if the color is green, the task is a letter task, which is to decide whether the presented letter is a consonant or a vowel. If the color is red, the task is a digit task, which is to decide whether the presented digit is even or odd. The response was made by pressing one of two buttons (indicated as Z and /) of a hand-held response glove by using right index and middle fingers. Consonant and even responses were assigned to one button and vowel and odd responses to another. The response to button mapping was balanced across participants.