Changing the “When” and “What” of Intended Actions

Humans often have to modify the timing and/or type of their planned actions on the basis of new sensory information. In the present experiments, participants planned to make a right index finger keypress 3 s after a warning stimulus but on some trials were interrupted by a temporally unpredictable auditory tone prompting the same action (experiment 1) or a different action (experiment 2). In experiment 1, by comparing the reaction time (RT) to …