[solved] Need help fixing ST-IAT problem

hughturpin

Hello,

I hope I'm posting this in the right place. I am experiencing a problem running my experiment in Opensesame. Basically, it is a single-target IAT. Participants have to press either the E or I key to categorise words on the screen. The experiment consists of three loops or blocks. The first is a training block, and the latter two are the test blocks. It works fine right up to the last word in each block. When it reaches the last item, Opensesame skips straight to the instructions for the next block without waiting for a categorisation keyboard prompt (so on the last item it skips forward without waiting for the participant to press E or I).

I am very new to Opensesame (and experiment design), so I'm sorry if there is an obvious fix I am overlooking here. However I've looked through it with a more experienced colleague and he can't figure out what the problem is either. I've included a screen grab of the overall experiment structure in case that helps.

eduard

Hi,

In order to help you, I would need more information, i.e. how did you implement the loop, the keyboard_response, the timeout and such. The problem can have many causes, it's hard to spot it at this point.

Thanks,

Eduard

hughturpin

Hi Eduard,

Each loop has 24 cycles which run one time each in a random order.

The loops consist of a sequence containing: 1) a fixation dot (duration 500 millisecs); 2) a sketchpad which displays the 24 cycles (these are JPEG images); 3) a keyboard response (correct response and allowed response are both entered as [Response], which is E or I depending on the cycle; timeout is set to infinite); 4) the logger.

Loops are separated by a sketchpad item with instructions for the next test followed by a keyboard response to begin (space bar).

Here's a link to an image:

Many thanks for any advice you are able to give me with this,

Hugh

hughturpin

Can anyone help with this? Deadlines are looming...

eduard

Hi,

So far I don't see an obvious mistake here. Do your initial fixation screen and waiting-for-response screen look identical? In other words, is it possible that the problem of not waiting in the very end of a trial happens always, but only after the last trial one can see it? Does the logfile look normal and if so, do your responses match your expectations? Finally, what happens if you tick the "Flash pending key presses at sequence start" box?

Sorry, but this issue is a bit unclear to me. Would you mind uploading the experiment, so that I can have a look on it directly?

Thanks,

Eduard

hughturpin

Hi Eduard,

No Problem. The log file seems normal and ticking the 'flush pending key presses' button hasn't made any difference to the problem. The fixation dot and response-waiting screens are different, and the problem definitely only occurs on the last trial in each loop. In all the others it waits for input. It's very strange.

I've uploaded the ST-IAT (two versions - both have the problem). To run the experiment you'll need the stimuli files for the file pool. There are dozens of them and Dropbox won't let me share folders without an email address. If you need to run the experiment rather than just look at it in Opensesame is there a way you'd like me to send you the stimuli folder?

https://dl.dropboxusercontent.com/u/49609310/STIAT1.opensesame
https://dl.dropboxusercontent.com/u/49609310/STIAT2.opensesame

Thanks again for taking a look at this,

Hugh

eduard

I'm not sure whether this is good or bad news, but you're experiment is running just fine for me. So, also on the last trial nothing will happen until the response key is pressed. After that however, it will go right away to the next loop. If you're just checking quickly whether the experiment works by pressing any key, it might appear as if the last element is skipped. But that's not what happens in your case?
Maybe it's a version thingy. Which one do you use? I have have OpenSesame 2.9.6 running on Ubuntu.

Eduard

hughturpin

Thanks for looking at it. That is really strange. I'm running 2.9.6 as well, but on horrible Windows 8. Maybe I should try it on a computer with a different operating system.

I've run through it thoroughly several times now, behaving as if I were a participant, and the last trial in each loop is definitely skipping the input on my computer. By the way, what did you use to populate the file pool? I'm using a load of JPEGs. Could it be related to that somehow? Just grasping at straws here...

eduard

I was using 2 JPG images of my own. One I used for with the sequence and the other for the instruction slides.

Could you maybe try to insert another element at the end of your sequence, e.g. another empty sketchpad presented for 50ms or something similar. In this way, you could force your last trials to be skipped at a later point in the sequence, so that responding won't be affected.

Btw., when you say that the logging file looks fine, does it also include the last trial? Does it appear just without response, or is it not present at all?

hughturpin

Hi Eduard - I don't know why, but it is working now. I uninstalled and re-installed Opensesame and opened the file again and now it runs properly. No idea why that worked, but I'm very relieved.

Many thanks for all your help!

eduard

Good to hear.

Good luck with your data. acquisition

Eduard