help on jittering a null event within active stimuli & can i erase after stimuli?

i have never worked with human subjects…i have never programmed and experiment, and i have never used SuperLab, so bear with me and PLEASE advise.

i am trying to run an experiment with a simultaneous presentation of picture and statement stimuli. when i try to separate out these two so that i can randomly pair them, i can get them both to show by doing as superlab suggests and keeping one invisible and asking only this one to erase before presentation. however, since the other stimuli doesn’t erase before presentation, it keeps appearing with the previous stimuli (such as the instructions or a null event) still on the screen…is there an option to erase after the presentation of a stimuli?

also, i want the null event to jitter within the active stimuli at variable durations, i’ve tried multiple approaches to this end, and cannot seem to achieve the desired effect.

does the delay between stimulus presentations have to be so long…the only way i can speed it up seems to be by speeding up the duration of presentation.

any help would be greatly appreciated.
thank you,
a frustrated graduate student

This sounds exactly like a phone call I took a few hours ago. If you didn’t speak with me, let me know and I’ll write up a response.