RT Experiment - Need Help

I’m new to SuperLab and I’m trying to create a simple reaction time experiment in which a participant must respond to a stimulus (Stroop word) presented for 500 ms. I want the stimulus to appear then disappear from the screen and then give the participant an additional 1500 ms to respond. Thus, one trial lasts for a total of 2000 ms. My problem is that I want this to all occur as one event such that the participant can respond at any time during the 2000 ms interval, including when the stimulus is present. I was able to create two separate events (one for the stimulus onset/offset and another empty interval for the additional 1500 ms). The only problem is that when I go to analyze the data on a given trial I see a NR for one of the two events and the correct RT for the other event. So, technically this experiment works, but I was just curious if there is a way to do it all as one event so I won’t have to manually sort through the data eliminating the NR’s?


You could definitely present the words as a movie. You may also be able to use the RSVP event type.

I have the same problem. How creates you two separate events (one for the stimulus onset/offset and another empty interval for the additional 1500 ms) ? Works by ramdomisated events correct ?

The vast majority of the time, event randomization is not what you want. In fact, it’s a feature that seems to have caused far more headaches than good since it’s always misinterpreted as the way to randomize stimulus lists. In almost every case, randomizing trials is what you want.

Hank, I am stuck in a situation in which I definitively need to randomize events to create random pairings of primes and targets in each trial. Since the events are taken from two separate stimulus lists, this would mean randomizing the lists, right?
Should I give up…?

Correct. Randomizing the lists would do what you need, but SuperLab doesn’t have this capability. The “randomize events” feature randomizes the order of the events as opposed to randomizing which events go in which trial.

A workaround that may or may not be plausible for you would be to use the “Participant Groups” feature. Since stimulus lists can’t be randomized, you can make multiple lists effectively making multiple versions of the experiment. With groups, you can pick which participants see which blocks, so you can make multiple versions of the same block using different sets of lists. Participants would then be randomly assigned a group by the toss of a dice (for example). It’s not an optimal solution, but it is a solution.

Thanks Hank, I’ll give it a thought.