I’m trying to set up an experiment that involves a movie clip being played continuously. While the movie is playing, the participant presses a key on the keyboard. Upon keypress, a tone is provided as feedback. I would like the tone delivered NOT instantaneously, but at some time delay.
One of the variable is the probability that the key press can produce the tone (which is 0%, 50%, 75% and 100%). How can i make that happen? should I make 2 trials with 0 and 100% chance of producing the sound, and then tweak it to obtain the 50% and 75% codnition, or is there a way to round it up into one event for each probability?