linking 3 events to a trial

[gjhaef]

I am trying to create the following experimental situation:

Present a cue stimulus for 800ms
Present a second cue stimulus for 500ms
Present a third stimulus to which the participant must respond

I created three events to represent the three stimuli listed above. However, I'm having a problem with the third event/stimulus. There appears to be some sort of delay with this event. For example, after the participant responds correctly, the stimulus stays on the screen for a little while before staring the event cycle again. This third stimulus also won't respond to a time limit. Whether I set the stimulus to end after 10ms or 500ms, it just stays on the screen the same amount of time. Any idea what is going on?

thanks,
Jerry

[gjhaef]

It looks like if the picture file extends the boundaries of the frame, then it causes a delay when cycling through the last event.

[gjhaef]

All of my stimuli are appropriate sizes and there is still a problem. The third event does not end as quickly as it should (both a delay when responding...and even if I select "end immediately")

[Hank]

Jerry,

Your expectations are not clear. You are talking about a delay, but it isn't clear what you mean by that. Are we talking about a 5ms delay or a 5 second delay?

Also, if you don't have an event created to explicitly erase the stimulus, then it isn't going to be removed from the screen until the next time the screen is erased.

Lastly, the default is to load stimulus files for one trial at a time. Larger images take more time. In the default configuration, stimulus files are loaded and drawn to an offscreen buffer between trials. This could also be a part of the delay you are seeing. To get around this, tell SuperLab to load all stimulus files prior to running the experiment (Experiment menu->Options->Memory Management->Load them all before running the experiment). SuperLab will then load all stimulus files prior to running the experiment (this may require a bit more memory depending on your stimuli). If you are using an offscreen buffer, that drawing will still be done between trials.


I hope this helps a little bit.