Image presentation experiment - same different

Hi there,

I am a new graduate student, designing my first experiment. Here is what I’d like to do:

Present a face, a mask, and another face
Participant will assess/respond same/different
I would like correct/incorrect and response time.

I would like to present 24 practice trials with feedback, and then 3 blocks of 80 trials for experiment.

I have 24 original faces of each gender; those 24 faces have been altered in two different ways, creating three different conditions.

The trials must be randomized, but presented same gender (i.e. male - mask - male or female - mask - female, not female - mask - male or vice versa).

I have managed to set up the instructions and a block in which a face, the mask and a second face are presented; however the face is always the same face/same condition, so always a “same” presentation.

thank you in advance for any help you can provide


Hi Tamara,

You have described your experiment nicely but haven’t said how it’s implemented in SuperLab. Can you provide more information or post your experiment?


Hi Hisham,

Thanks so much for the reply. Attached is the experiment so far. Sorry for the delay – it was on a school computer :).


eyebrow trial.sl4 (13.5 KB)

Both of your events are using the same stimulus list. Therefore, within the same trial, the two events will reference the same stimulus. You will need two separate stimulus list: one for the first event and the other for second. Items within these lists will be paired up one-to-one, so item x in list A will be paired with item x in list B. (A1-B1,A2-B2,A3-B3…).

I hope this helps!

Thanks so much for the information! Is there a way to have superlab randomize those lists?

thanks again,


The lists themselves cannot be randomized, but you can randomize the trials in the blocks which will randomize the appearance of the matched pairs.

Thanks so much! I will play with this and get back to you :slight_smile:


Yay, that worked! :slight_smile:

Okay, so now I have one problem and one question.

Problem: I am getting male and female faces presented in the same trial, ie male face, mask, female face, when I only want male face, mask, male face or female face, mask, female face. Can I fix this with codes?

Question: I would like to give feedback for correct/incorrect during the practice trials and am not sure how to do this. Is there a way I can tell Superlab that same trials are those in which the same file is presented? I would think this would be the easiest way.

thanks so much!!


I suspect you may have misinterpreted the detailed about how items from one list will be paired with items from the the other list. (no, codes won’t fix it.) The first stim list is what will show in the first event, and the second stim list is what will show in the second event, so you’ll need to make sure you correctly pair up the items in the two lists. If you are wanting to definitively separate male and female faces, it may be easier to do with four stimulus lists (but this isn’t necessary).

Ok, I was thinking I could solve the problem with four lists, I thought I would then have to have four events. Perhaps I can figure out a way to set it so it’s events 1 and 2 OR 3 and 4, and have that randomized.

thanks for your help


You’ll need to also duplicate the trial. Events 1 and 2 would be in one trial while events 3 and 4 would be in the other. The trials will be expanded separately, and the block won’t distinguish between the trials when randomizing.

Ok, I have hit a wall. Three steps forward, two steps back I guess. Any suggestions?

thanks so much for all your help,


eyebrow trial2.sl4 (14.6 KB)

Doing this with folders really complicates things, since all you can do in the stim list editor is change the order of the folders–you can’t change the order of the items inside. I’d recommend putting the actual stimulus files in the stimulus lists.

Then, keep in mind that item 10 in list A is always paired with item 10 in list B. When using folders, it wouldn’t be abundantly obvious which items would be paired together.

Also, your two Male stimulus lists are in the same order, and you DON’T want to randomize the events in the trial.

To simplify things, though, you don’t have to duplicate your Mask events for the two different trials unless you explicitly WANT them to be different. You can link the same event to more than one trial.

Awesome, thanks so much. I will implement tomorrow and let you know how it goes.


Ok, so I’ve been playing with this and have hit a wall. Using files rather than folders right now, however I may change that later – I want a new random presentation of stimuli for each participant and I don’t think superlab can do that for me. I may just use a random number generator to generate random “lists” and then put those together in folders ahead of time.

The problem I’m having right now is giving feedback during practice trials. Because I want to present my last stimulus for 150 ms, then wait for participant feedback before starting the next trial, I am having trouble. I can do this if I have a separate event that is “input.” However then I can’t code my trials same or different, and corresponding responses. If I check the check box for both participant response and time limit, the program moves to the next event after 150 ms because that occurs first. Hope that all makes sense.

When I run the actual experiment trials, I can just use the input event as long as the data file picks up the file names that were presented and the response – I can program a variable in my stats software as to whether the response is correct or not. If the data file can not pick up file names, I guess I will have to go through and manually set each trial as a same or different. bummer.

thanks for your help,