Random presentation times?

[rjrydell]

Hey Blair,

I read the page you mentioned above ... http://www.empirisoft.com/directrt/h...dom_values.htm ... and I was wondering how I could randomly present a sound while participants are reading a sentence - the purpose of the sound would be to distract them. I would want the occurrance of the sound to be random (so participants cannot predict it) and the sound, but not the sentence, would be turned off by a keypress (the sentence would be turned off by a pre-set time or a different keypress). This would be similar to a Petty et al. (1976) distraction task. Any thoughts or any posts on this issue?

Best,

BJ

[jarvis24]

Playing a random sound during another stimuli is not a problem. I would probably just randomly select it from a stim file. Have an embedded silence in the sound file to create an onset and then, without delay, present the sentence. Then take two RTs to the sentence--one for the sound and a second one for the sentence itself--using separate valid keys for each. There may be other ways, but that's off the top of my head. You can also do a search on here for "probe" -- you might find some useful links with that--both for DirectRT and MediaLab.