Repeating Stimuli Until Key Press

[jarvis24]

Maybe a couple ways to do it. Can you give me an approximate range of flashes possible on each trial, for how long (ms) each flash would occur and the interval (ms) between flashes?

[iowa]

Each flash would occur for about 350 ms and the interval between each flash would probably be about 1-2 seconds. The idea is that the subjects see flashes of the stimulus repeatedly until they feel comfortable enough answering a question about it. Some people may only need to see the stimulus flash once, but we'd like it to repeat as many times as the subject needs (but only for a third of a second at a time).