[solved] SOA - stimulus onset asynchronies

Federica

In my experiment, I would like to vary parametrically the onset asynchronies of two stimuli (auditory and visual stimuli). For example, the range of stimulus onset asynchronies would be: -100 ms; -50 ms; 0; 50 ms; +100 ms.

How could I manage this problem in OpenSesame?

Thanks in advance!

Edwin

Have a look at this thread, it contains the code that should (in principle) be able to do it, as well as a link to a setup that would allow you to do audiovisual experiments with high timing accuracy.

Good luck!

Federica

Thank you Edwin and, of course, Raquel for your help. However, I still have some problems, maybe since I’m noob about programming!
In my experiment, as I told you, I have a circle and a auditory stimulus that are presented for different SOA.
Here my few script lines:

# Here draw the circle.
set duration "10"
set description "Displays stimuli"
draw circle 0 -64 256 fill=0 penwidth=1 color=#ffffff show_if="always"

...

#Here the beep
set volume "1"
set description "Plays a sound file in .wav or .ogg format"
set sample "SoundOut2.WAV"
set pitch "1"
set duration "sound"
set stop_after "0"
set pan "0"
set fade_in "0"

...

#Here the inline_script for different SOA, as Raquel did. 
if SOA == -10 or SOA == -30 or SOA == -50 or SOA == -80 or SOA == -100 or SOA == -150 or SOA == -200 or SOA == -250 or SOA == -300:
    beep.play()
    self.sleep(abs(SOA))
    circle.win()

        elif SOA == 10 or SOA== 30 or SOA == 50 or SOA == 80 or SOA == 100 or SOA == 150 or SOA == 200        or SOA == 250 or SOA == 300:
    circle.win()
    self.sleep(abs(SOA))
    beep.play()

else:
    beep.play()
    circle.win()

… I’m not sure if circle.win() is a correct command. In fact, the debug output is:

Traceback:
File "dist\libopensesame\inline_script.py", line 121, in prepare
File "", line 5
circle.win()
^
IndentationError: unindent does not match any outer indentation level

I am not able to write the right command to view the stimulus on the screen, according to the SOA. Any suggestion?

Edwin

It seems like the indentation isn't right, which means that you either have too little or too many spaces/tabs in front of the code. Directly after an if statement, Python expects there to be a tab. And if you continue the statement, it expects there to be a elif or else command on the same level of indentation. An example:

This is code that works:

if something:
    this = ok
else:
    this = also_ok

This is code that does not work:

if something:
this = not_indented_enough

And this doesn't either:

if something:
    this = ok
    else:
        this = not_ok_else_is_indented_to_far

So to fix the code you posted, you should decrease the indentation of your "elif" in line 6:

#Here the inline_script for different SOA, as Raquel did. 
if SOA == -10 or SOA == -30 or SOA == -50 or SOA == -80 or SOA == -100 or SOA == -150 or SOA == -200 or SOA == -250 or SOA == -300:
    beep.play()
    self.sleep(abs(SOA))
    circle.win()
elif SOA == 10 or SOA== 30 or SOA == 50 or SOA == 80 or SOA == 100 or SOA == 150 or SOA == 200 or SOA == 250 or SOA == 300:
    circle.win()
    self.sleep(abs(SOA))
    beep.play()
else:
    beep.play()
    circle.win()

If that does not work, remove all of the spaces in front of all the lines of code. Then insert tabs in all lines, apart from the lines that begin with if, elif or else.

Good luck!

Edwin

Also, it just occurred to me that you will most likely not have the beep and the circle set up in a similar way as Raquel has. We should fix that too!

Add the following to an inline_script item somewhere at the start of your experiment:

# import the libraries that we will need
from openexp.sampler import sampler
from openexp.canvas import canvas

# create the sound, using your file
exp.beep = sampler(exp, exp.get_file('SoundOut2.WAV'))

# create the display with a central circle
exp.circle = canvas(exp)
exp.circle.fixdot()

Now use a slightly adjusted script to present the stimuli:

# first, check the SOA
SOA = exp.get("soa_var") # change 'soa_var' to the variable you use for the SOA!

# then check what to do
if SOA == -10 or SOA == -30 or SOA == -50 or SOA == -80 or SOA == -100 or SOA == -150 or SOA == -200 or SOA == -250 or SOA == -300:
    exp.beep.play()
    self.sleep(abs(SOA))
    exp.circle.show()
elif SOA == 10 or SOA== 30 or SOA == 50 or SOA == 80 or SOA == 100 or SOA == 150 or SOA == 200 or SOA == 250 or SOA == 300:
    exp.circle.show()
    self.sleep(abs(SOA))
    exp.beep.play()
else:
    exp.beep.play()
    exp.circle.show()

Please do note the potential pitfalls mentioned in the thread I linked to! Sound timing is different to get precisely right (not just for OpenSesame, by the way).

Federica

Edwin, thank you for your precious help: the experiment works perfectly!

Greetings!

@};- @};- @};-

Edwin

Very good to hear, I'll mark this as solved. Good luck with your study!