Trying to generate two sizes of the same image in random order

Builder
1

If this template helps then use it. If not then just delete and start from scratch.

Mac
PsychoPy version 1.84.2
Standard Standalone

Hi,

I am trying to build an experiment that tests the effect of image size on a rating of that image. The user will be presented with both large images and small images from the same pool. The images will be presented randomly eg. small_image_2, small_image_4, large_image_9, small_image_3, large_image_2 etc. until the user has seen a small and large version of each image.

Currently I have a random loop surrounding the large_image and small_image routines. However the experiment runs like large_image_3, small_image_3, large_image_9, small_image_9, large_image_4, small_image_4 etc. How can I change this to be as I described in the first paragraph ie. truely random?

Thanks

2

  1. Your conditions file should just have a single column (containing both large and small image file names).

  2. You should have only one routine, within a single loop. The image component on that routine just displays whatever image is next. The loop will handle randomising these.

3

Thanks for your reply.

Is there any way to do this using the same files, but changing the size in Psychopy? Otherwise I would have to go through all images and add a border to make them appear smaller. Changing the size of the original file doesn’t work as Psychopy sets the size of the image.

4

You can set the size of an image the same way you can set most attributes in Psychopy using the $ sign. You would have a column for your image files in your conditions file and a column for the size (default is in normal units - so 1 = full size, 0.25 = quarter size etc).
In the image component you would have $img and $imgSize in the image and size boxes. That way the size would be set on every repeat like the image.

6

Thanks Oli!

That solved the issue.