[solved] Using Parallel plug-in in OpenSesame

Sachinthana

I want to display two blocks (say squares) that will blink with two different frequencies, on the screen. How can I achieve this using the 'parallel plug-in' in OpenSesame?

Josh

Hi,

I have no experience in using the parallel plug-in myself (and I've also heard that it is a bit unstable), but I do think this is achievable without the parallel plug-in in the first place. How well it works depends on the desired frequencies though; very high frequencies may not be displayed properly.
The idea would be to create 4 canvases in an inlinescript, one for each 'state', i.e., a canvas with two squares on, a canvas with one square on and one square off, etc. In the run phase, you start a timer by means of start_time = self.time(). Next, you keep track of time in a while-loop, and present the canvases accordingly. Say these are the frequencies and states (1 for on, -1 for off):

  square1_freq = 12
  square2_freq = 8
  square1_state = 1
  square2_state = 1 

As an example, you want the second square to go on/off at 1/8*1000 milliseconds and all multiplications of this value. Hence, you get something like this:

  end_reached = False
  stimuli_presentation_duration = 2000

  current_multiplication_sq1 = 1
  current_multiplication_sq2 = 1      
  while end_reached == False:
         canvas_change = False
         current_time = self.time() - start_time
         if current_time >= float(1)/square1_freq*1000*current_multiplication_sq1:
               square1_state = square1_state * -1
               current_multiplication_sq1 += 1
               canvas_change = True
         if current_time >= float(1)/square2_freq*1000*current_multiplication_sq2:
               square2_state = square2_state * -1
               current_multiplication_sq2 += 1
               canvas_change = True

         if canvas_change == True:
               if square1_state == 1 and square2_state == 1:
                      canvas1.show()
               elif square1_state == -1 and square2_state == 1:
                      canvas2.show()
               elif square1_state == 1 and square2_state == -1:
                      canvas3.show()
               elif square1_state == -1 and square2_state == -1:
                      canvas4.show()

         if current_time >= stimuli_presentation_duration:
               end_reached = True      

Let me know if this works.

Cheers,

Josh

Sachinthana

Hi Josh,

Thanks for the tip.
I'm a kinda new to OpenSesame and it took me a while to understand the use of inline code. I compiled the code and run it with 4 sketchpads c1, c2, c3, c4 in the experiment modifying your code as shown below.

start_time = self.time()

square1_freq = 12
square2_freq = 8
square1_state = 1
square2_state = 1

canvas1 = canvas()
canvas2 = canvas()
canvas3 = canvas()
canvas4 = canvas()

canvas1.c1()
canvas2.c2()
canvas3.c3()
canvas4.c4()

end_reached = False
stimuli_presentation_duration = 2000

current_multiplication_sq1 = 1
current_multiplication_sq2 = 1      

while end_reached == False:

    canvas_change = False
    current_time = self.time() - start_time
    if current_time >= float(1)/square1_freq*1000*current_multiplication_sq1:
        square1_state = square1_state * -1
        current_multiplication_sq1 += 1
        canvas_change = True
    if current_time >= float(1)/square2_freq*1000*current_multiplication_sq2:
        square2_state = square2_state * -1
        current_multiplication_sq2 += 1
        canvas_change = True

    if canvas_change == True:
        if square1_state == 1 and square2_state == 1:
            canvas1.show()
        elif square1_state == -1 and square2_state == 1:
            canvas2.show()
        elif square1_state == 1 and square2_state == -1:
            canvas3.show()
        elif square1_state == -1 and square2_state == -1:
            canvas4.show()

    if current_time >= stimuli_presentation_duration:
        end_reached = True

But it reported me the following error.

  File "dist\libqtopensesame\misc\process.py", line 140, in run
  File "dist\libopensesame\experiment.py", line 390, in run
  File "dist\libopensesame\item_store.py", line 94, in execute
  File "dist\libopensesame\item_store.py", line 126, in prepare
  File "dist\libopensesame\sequence.py", line 106, in prepare
  File "dist\libopensesame\item_store.py", line 126, in prepare
  File "dist\libopensesame\sketchpad.py", line 103, in prepare
  File "dist\openexp\_canvas\xpyriment.py", line 98, in prepare
  File "dist\expyriment\stimuli\_visual.py", line 752, in plot
  File "dist\expyriment\stimuli\_visual.py", line 289, in surface_size
  File "dist\expyriment\stimuli\_visual.py", line 391, in _get_surface
  File "dist\expyriment\stimuli\_rectangle.py", line 112, in _create_surface
  error: Invalid resolution for Surface

Can you please help me to get out of this?

Cheers.

Sachinthana

Josh

Hi Sachinthana,

How did you construct (i.e. place the squares on) your canvases? At first glance it seems to me that something went wrong there. You could try to present your canvases in a simplified manner, like this:

   canvas1.show()
   self.sleep(5000)
   canvas2.show()
   self.sleep(5000)   # et cetera.

and see if that works normally.

Cheers,

Josh

Sachinthana

Hey Josh,

It worked. Thank you very much.