Eamon, The Kubovy Lab @ UVa is doing what you describe (if I understand you correctly) by using multiple presentation/viewport instances for each component of each trial (all sharing the same screen). For example, in one experiment we present: 1) A fixation spot 2) A mask 3) The stimulus 4) A response screen Each of these is a stimulus tied to a Presentation and Viewport. A "show()" convenience method has been added to each class to reset the Presentation object and call its "go()" method. The inner "loop" of this experiment looks something like this: ---------------------------- # Define the trials conditions = setupTrialData(sequenceFileName) breakNotice = Instructions(screen, "Take a moment to rest.") for i, trial in enumerate(conditions): lattice.setTrial(trial) fixationPres.go() mask.show() lattice.show() response.show() logger.log(trial) if ((i+1) % session.breakInterval) == 0: breakNotice.show() ------------------------------- The power of the Presentation object becomes apparent when you have Stimulus parameters which change over time (e.g. a function of 't') or between trials. You are very welcome to download our source code and play with it however you like. Instructions are available here: http://kubovylab.psyc.virginia.edu/index.php/How_to_Get_The_Source_Code For a quick sense on how we are using VisionEgg, some example screen shots are available here: http://kubovylab.psyc.virginia.edu/index.php/Main_Page Along with instructions on how to get it running, if interested: http://kubovylab.psyc.virginia.edu/index.php/Perception_Toolkit_Development_Environment_Setup Good luck! Simeon Fitch -- Simeon H.K. Fitch, Owner Mustard Seed Software Charlottesville, VA 22901 On 1/23/06, Eamon Caddigan <ecaddiga@xxxxxxxx> wrote: > Hi all, > > Our lab is getting ready to run its first experiments that make use > of Vision Egg. They work well enough, but I've been unable to make > use of the Presentation class for my main loop without the result > feeling uncomfortably kludgey. > > I'm happy to write my own main loop. However, since the code I write > now may be used by other people in the lab as we continue > transitioning to Vision Egg, I want it to fall in line with the > current best practices. > > I'd probably feel better about this if the examples distributed with > Vision Egg included a multi-trial experiment. > > Thanks, > Eamon Caddigan > > ====================================== > The Vision Egg mailing list > Archives: //www.freelists.org/archives/visionegg > Website: http://www.visionegg.org/mailinglist.html > =====================================The Vision Egg mailing list Archives: //www.freelists.org/archives/visionegg Website: http://www.visionegg.org/mailinglist.html