I would like to produce a within-trial delay period composed of interval A, distractor flash, and interval B. I need help to produce some conditional expression such that interval B can always be chosen based on a random interval A. Intervals A+B+distractor stimulus always sum to a fixed total delay period (for a total of either 1, 2 or 4 sec).
Here is a brief description of the trial protocol:
At the beginning of each trial participants will fixate (for 1 sec) at a central fixation mark on a black background. A visual cue is displayed for 200 ms. A delay period (1, 2 or 4 sec) follows the cue, and participants will continue to fixate. Within each delay period a distractor stimulus briefly appears once, and the time of appearance of the distractor within the delay period is random from trial to trial. A signal for response follows the delay, and a blank screen (for 1 sec) after the response until the end of the trial.
Is there a way to determine interval B depending on a random interval A within each trial?
Many thanks in advance.