Help! Complete newbie, completely lost on how to set mouse click regions and repeat audio files

etwollum

Hi,
I'm very new to OpenSesame and I'd like to find out how to do two things, for starters:

1. How to repeat an audio file for a practice round after a certain number of milliseconds - I want to play the file after 500ms, then repeat the audio file after a 1500ms break

2. How to set a sketchpad with clickable regions - I want my participants to be able to see a sentence written on the screen and then be able to click on individual words in the sentence, which will present them with either positive or negative feedback

Can anyone help, or would anyone else be willing to share a script that they used for an experiment with audio stimuli? I'm feeling completely lost at the moment.

Cheers,
Emma

Pascal

Hi Emma,

regarding your second point: If you want to define clickable regions on a sketchpad, you could use the mousetrap_response plugin for OpenSesame: https://github.com/pascalkieslich/mousetrap-os

However, one caveat regarding your specific design: using the plugin you can easily define a rectangular region on a screen that represents a button - this is done in the pixel metric used by OpenSesame sketchpads. However, if this regions differs for each stimuli because of the word length and word position in the sentence, it will likely be challenging to come up with the corresponding screen coordinates beforehand.

Best,

Pascal

Josh

Hi Emma, welcome to the forum!

To start off with your second question, when you collect a mouse response (with the mouse response item), it logs the button but also the X and Y-coordinates. You can use these coordinates to provide participants positive or negative feedback; but as you might have anticipated, this would require you to specify a set of coordinates belonging to the region (in your case a word) for which the feedback should be positive. This inevitably requires some coding (using the inline_script item).

For starters, look up how you can create a canvas (as alternative to the sketchpad item) here: http://osdoc.cogsci.nl/3.1/manual/python/canvas/
You will see there is also a canvas.text_size function, which returns the amount of pixels of your sentence, or an individual word (e.g. your_canvas.text_size('hello')[0] returns the amount of pixels in the horizontal dimension occupied by 'hello' on your canvas; you do need to make the canvas named your_canvas first though). If I wanted to have the coordinates of a specific word in my sentence, I might do the following:

  sentence = 'This is just a sentence' # And let's say 'is' will be our correct word
  my_canvas = self.offline_canvas()
  my_canvas.text(sentence) #this puts the sentence on the canvas

  sentence_startpoint_X = my_canvas.xcenter() - 0.5*my_canvas.text_size(sentence)[0] 
      # in order to find the startpoint coordinate, we have to move half the sentence length to the left from the screen center

  left_coordinate = sentence_startpoint_X + my_canvas.text_size(sentence.split(' ')[0])[0]
       # 'is' is located to the right of the sentence's first word, so from the startpoint we have to move a distance equal to the sentence's first word to the right, to find the leftmost coordinate of our region

  right_coordinate = left_coordinate + my_canvas.text_size(sentence.split(' ')[1])[0]

Now I have the two coordinates, in between of which my mouse response x-coordinate should be for the response to be correct. Determining whether the response is correct will also have to be done in an inline script.

If you've become acquainted with this scripting, then your audio file shouldn't be a problem anymore either. You can find the sampler functions here: http://osdoc.cogsci.nl/2.8/python/sampler/ And you can use a simple self.sleep(1500) to have a 1500ms break.

Cheers

Josh

etwollum

That's brilliant, thanks Josh! The only thing I don't understand is where I actually get the 'canvas' option to insert into the flow of my experiment, as there's no shortcut for it like the sketchpad?

Josh

Hi Emma, you'll have to use the inline_script item, and include the lines of code as indicated by the manual (and in the example I gave above).

You thus build your screen using that code, and then you actually show the canvas by inserting my_canvas.show() in the run-phase of the inline_script. (if your canvas is named my_canvas; that is up to you).

You can also do this tutorial http://osdoc.cogsci.nl/3.1/tutorials/intermediate/ as it shows how to use inline_scripts and canvasses.

Cheers

Josh