Change Blindness Question

[Cathycjos]

I am having trouble programming a change blindness experiment using Direct RT.


The main issue is that in the Time column I want Direct RT to show stimulus for 250 ms and then show the next stimulus for 250 ms in the same trial, however, I also am hoping to program Direct Rt so that we can measure participants reaction time IF/When they notice a change in the picture (by clicking on the spacebar).


For each trial, the participant will see Stim 1 (picture1 ), Stim 2 (blank screen), Stim 3 (picture 2), Stim 4 (blank screen). This loop will be repeated several times. This is done to look like a flicker effect. So that participants won't notice the change for the first few stimuli (but the stimulus need to be timed in order for the flicker effect to work).


So I want to programme for the stimulus to be presented for a specific amount of time (250ms) or until a response is made by the participant. However, from reading the manual it seems that this is not possible as I can only do one or the other? Is this possible on DIrect RT?


I hope you can help.