[solved] Lexical decision task; Key response acts weird (have to push twice)

Cerniane

Hi all:),

I am using open sesame for the first time for one of my experiments. I am using a lexical decision task. I want to present 30 words (10 relevant existing words, 10 irrelevant existing words, and 10 non-words) and I want to present all the words twice and randomized.

My issue is this: When I run a test trial, open sesame does not respond immediately to my key board response. I have to react twice before it goes to to next word (all words are preceded by a fixation dot and I have created the words with the Sketchpad function). I want to measure reaction times, so the fact that it does not seem to work is a big issue. Can anyone tell me how to fix this? I am probably doing something wrong, but I cannot figure out what (I specified the correct and acceptable responses for the Keyboard response function).

Hope you can help me!!!

sebastiaan

Hi,

Welcome to the forum!

I'm guessing that you have set the duration of the sketchpad that contains the word to 'keypress' and have this sketchpad followed by a keyboard_response. Is that right?

If you want the word to stay visible until the participant responds, you should set the sketchpad's duration to 0, so that it doesn't block the experiment, and have it followed directly by a keyboard_response. This is explained in Step 6 of the step-by-step tutorial:

• http://osdoc.cogsci.nl/tutorials/step-by-step-tutorial/

Cheers!
Sebastiaan

Cerniane

thank you so much for your reply!

I didn't exactly do what you said I might have done, but what I did do was the following:

I had a sketchpad item (the words) with a duration 500 ms. After that I had the keyboard_response item with a duration of 5000 ms.. you think that that was simply the mistake? The idea was to present the words for 500ms and measure peoples' reaction time to the words presented and I allowed them to give a response as long as it did not exceed 5000 ms.

I now used step 6 from the tutorial and set the duration of the words to 0 so that it goes directly to collecting the keyboard response (which I now have still set at 5000ms). It now doesnt show the problem anymore that I was having before.. so i think it works now. Does it sound logical to you? Sorry for asking a perhaps very obvious thing, but I am still a noob when it comes to open sesame .

It seems then too, if I get it correctly, that if i want to present the words for only 500 ms, i should give them only a 500ms keyboard_response time. is that correct?

Anyways, thank you very much once again. I am really impressed with how quickly you responded. So far this forum is a blessing !!!

lvanderlinden

Hi,

Does it sound logical to you?

Yes! I think what was going on in your previous design, is that the experiment freezed/paused for 500 ms after sketchpad onset. Therefore, no response could be collected during this interval. Only after 500 ms, your experiment advanced to the next part, namely the keyboard_response item. So my guess is that the original problem was not really that you had to press twice, but that your first keypress fell within the 500 ms freeze. Does that make sense?

If i want to present the words for only 500 ms, i should give them only a 500ms keyboard_response time

Exactly!

Don't hesitate to ask any further questions!!

Cheers,

Lotje

Cerniane

hey! thank you very much! everything seems to be working now. I am very very happy with this:)! I will definitely post again if I have any further questions!