Hi Andrew the VE-fMRI project goes on..now I can read in by means of a simple GUI (thanks to wxPython) the subject ID and the stimulus-file (where the to be shown stimuli are listed). One problem: the following code snippet is the essential part yielding a problem: this code shows me (my_debug_msg), that the screen.clear() routine takes most of the times between 20 and 60ms. ..why this? while (not pygame.event.peek((QUIT,KEYDOWN))): while (not TRIGGER_RECEIVED): poll the Lpt... my_debug_msg.append('before clear.screen [ms]: ' + str(1000 * (VisionEgg.time_func()-start_time)) ) screen.clear() my_debug_msg.append('after clear screen [ms]: ' + str(1000 * (VisionEgg.time_func()-start_time)) ) viewport.parameters.stimuli = [preloaded_stimulus_list[stim_index]] #update the viewport viewport.draw() swap_buffers() -- I cannot explain it. Thanks for a hint christoph -- p.s. the preloaded_stimulus_list[stim_index] comes from: -- # Create a list of TextureStimulus instances, one with each of your texture images. preloaded_stimulus_list = [] #empty at first for stim_index in range(num_images): #for all stimuli except the null-event create a texture object if not photoX[stim_index] == nullevent: # Read the texture file texture = Texture(photoX[stim_index]) # Add to list of TEXTURES x = screen.size[0]/2 - texture.size[0]/2 y = screen.size[1]/2 - texture.size[1]/2 # Load the texture to OpenGL, prepare for display stimulus = TextureStimulus(texture = texture,size = texture.size, lowerleft=(x,y)) else: #for the nullevent, just append the nullevent-indicator stimulus = nullevent # Add to list of stimuli preloaded_stimulus_list.append( stimulus ) viewport = Viewport( screen=screen) -- -- Christoph Lehmann <lehmann@xxxxxxxxxxxx> University Hospital of Clinical Psychiatry ====================================== The Vision Egg mailing list Archives: //www.freelists.org/archives/visionegg Website: http://www.visionegg.org/mailinglist.html