[solved] Touch Screen Corsi Task - Borrowing a little code!!

Comments

• sebastiaan

  January 2014 edited 8:42PM

  Hi Katherine,

  Welcome to the forum!

  The variable maxClickErr in this script indicates the maximum distance in pixels that a touch can be from a specific target point, indicated by xTarget and yTarget. So the acceptable area is a circle around the target point with a radius of maxClickErr pixels.

  Does that answer your question?

  Cheers,
  Sebastiaan

  
  
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• psukar

  January 2014 edited 8:42PM

  Thank you, yes of sorts, I think my problem is that I've used this code thinking it would be appropriate for my task. Basically the corsi blocks task uses squares as targets. To this extent I've used the above code so that now it draws an acceptable target circle around the square which is largely fine as the margin for error is so small outside of the target, but is there a way that I could adapt the above code specifically for squares?

  Thank you,
  Katherine.
• sebastiaan

  February 2014 edited April 2014

  Hi Katherina,

  Sure, the dx and dy variables indicate respectively the horizontal and vertical deviation from the target center. So defining an acceptable square would be something like this:

  Update: Corrected script

  # Determine `correct` variable
  if clickErr >= abs(dx) and clickErr >= abs(dy):
      exp.set('correct', 1)
  else:
      exp.set('correct', 0)
  

  Cheers,
  Sebastiaan

  
  
  Check out SigmundAI.eu for our OpenSesame AI assistant!
  
• psukar

  April 2014 edited 8:42PM

  Hi Sebastiann,

  thank you for your help so far. I now might need a little more though, I've changed my design slightly so that it uses rectangles as stimuli which are 151 x 117 pixels in size and like before I need them to be targets for the touchscreen version. I'm currently trying to adapt the first piece of code on this thread to use rectangles, trying to work it out considering that you explained how I would make it relevant for squares. However I am yet as able to do that. I was wondering if you would be able to give me the full code for using rectangles as targets? Would I need to remove the square root part of the original code in this thread?

  Sorry,

  Thank you,
  Katherine x
• sebastiaan

  April 2014 edited April 2014

  Hi Katherine,

  I now notice that there is a mistake in my previous post. You should not compare clickErr against the horizontal (dx) and vertical (dy) deviation, but maxClickErr. And if you want to use a rectangle instead of a square, you need to use different maximum errors for the horizontal and vertical. For example like so:

  Update: Corrected script

  from math import sqrt
  # The maximum error from the target center
  maxClickErrX = 115/2
  maxClickErrY = 117/2
  # Use Pythagoras to determine the click error and set
  # the variable `correct` to 1 (correct) or 0 (incorrect)
  # depending on whether the click error is small enough.
  # Because the cursor coordinates have 0,0 at the top-left
  # and the sketchpad coordinates have 0,0 at the center,
  # we need to compensate for the display size.
  xc = self.get('width') / 2
  yc = self.get('height') / 2
  # Determine x and y error
  dx = self.get('cursor_x')- xc - self.get('xTarget')
  dy = self.get('cursor_y')- yc - self.get('yTarget')
  # Determine `correct` variable
  if maxClickErrX >= abs(dx) and maxClickErrY >= abs(dy):
      exp.set('correct', 1)
  else:
      exp.set('correct', 0)
  

  So you basically just check if the horizontal and vertical deviation are smaller than or equal to the maximum click error. Pretty straightforward, really. Does that make sense?

  Cheers,
  Sebastiaan

  
  
  Check out SigmundAI.eu for our OpenSesame AI assistant!
  
• psukar

  April 2014 edited 8:42PM

  Hi Sebastiaan,

  thank you for your help, I pasted that code in t replace what I had before and changed the 115 to 151 because that's the width of my rectangle, but it now isn't registering any clicks as correct at all. I'm not sure why. No matter how close to the centre the results just keep registering 0 correct. I will continue to have a look at this, any ideas though?

  Thank you again for your help,
  Katherine.
• psukar

  April 2014 edited 8:42PM

  Also what does abs stand for? The rest I think I understand. Thank you, Katherine.
• psukar

  April 2014 edited 8:42PM

  Wait I think I may have done it, the arrows should be the other way around? >=abs(dx)?

  thankyou
• Edwin

  April 2014 edited 8:42PM

  Hi Katherine,

  The function abs() is to calculate the absolute value of a number. This is defined as the square root of the square of the original number, which basically comes down to the same number as you put in, but without the minus sign. Examples: abs(3) == 3, and abs(-3) == 3.

  It seems the "smaller than or equal" sign should have indeed been a "greater than or equal". Sorry about that!
• sebastiaan

  April 2014 edited 8:42PM

  It seems the "smaller than or equal" sign should have indeed been a "greater than or equal". Sorry about that!

  Oops 8-}

  
  
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• psukar

  April 2014 edited 8:42PM

  Its o.k, thank you both lots, you've been a massive help and I think I'm one step closer now to understanding programming, she sais . . I think I finally have my Corsi task up and running though, stopping rule and touch screen response working, thank you. I will spread the word!!!!

  thanks, kat x