2 Alternative Forced Choice

Hi, I am trying to use a 2 alternative forced choice paradigm in my experiment, where participants will get two words on the screen at the same time: one they studied and one they didn’t. Each word will come from its stimulus list. Is it possible to randomize the location of these words (one being on the left side of the screen and the other being on the right)? Also, could I get the locations of the words in the data output?

Use the Trial Variable for Screen Location to randomize the position of your photos. This is found under the Experiment menu within SuperLab. Once you create your Trial Variable, go into the Event Editor, Settings, and then Position. Under “The position of the picture is:” select Variable. Under “Select the variable” choose the Screen Location Trial Variable you created.

Hi Monika,
Thanks for that, I’m most of the way there. I would like to randomize the locations of the words on the screen, so sometimes a word from the studied list will be on the left (and thus a word from the non-studied will be on the right), and sometimes on the right.

Please see the attached sample experiment. In the Edit Trial Variable screen, both “Random with no Replacement” and “Each Trial” should selected for both your screen locations.

Regarding SuperLab recording the locations, the location on the screen will be recorded. However, you do have to make sure your first event is set to end on a time limit, under the Input tab. You can set a time limit to 1 ms.

right.left.sl4 (4.55 KB)

I am working on an experiment where we need to show an image and the word related to that image (in same window) and in the next window show a list of 6 words and their corresponding images to the user to select the the correct image&word earlier shown.

I need help in accomplishing 2 tasks:

  1. I am able to show the list of words and images together using Trial variable (and levels option), but since the word and the images are coming from 2 different lists, I am not able to show the images next to the word which they belong to.

  2. The user has to select the correct word or the image by clicking on it and, I need to store the user’s selection in the data file to know which selection user made.

Please let me know what can be done for these 2 tasks.

I suggest for the first screen using one stimulus list for your words and another list for your pictures. Then, for the second screen create an additional 5 lists for your words and the same for the pictures. This way you can display a total of 6 words and 6 corresponding images on the screen at one time.

In our experiment if we create an additional 6 lists for the words and the same for the pictures, then it would make our experiment very lengthy as we have large number of items to show to user and then display 6 words and pictures for each of those item in the second screen.

Is there an alternative way to keep 6 words in one list and 6 pictures in other list so when we randomize the list of words then the pictures also get randomized in the same order(in second screen) so that say for example, 3rd word from the list of words and 3rd picture from the list of images always appear next to each other while displaying 5 options together?
Are there similar experiments that we can refer to?

Also, how can we record the user’s selection by making them to click on a word or the picture.

I still recommend using stimulus lists. If you don’t you will need to create many events. Also, it makes no difference in terms of SuperLab’s loading speed.

Regarding your second question about the order of the stimulus lists, what you are requesting is the default behavior for SuperLab. For example, the first item within “stimulus list 1” will be paired with the first item of “stimulus list 2.”

Also, how can we record the user’s selection by making them to click on a word or the picture.

You can use the Mouse/Touch Screen option under Participant Input. Here you can define the areas the participant clicks on. Also under the Options tab make sure you have “Save the response to the collected data file” checked.