Duration time presentation stimuli

CélineG · January 2016

Hello !
I have prepare a Stroop modified task. I wish to reccord reaction time of participants. When the stimulus appears on the screen, participant have to choose between 4 keys on the keypad. Open Sesame reccords correct responses and reaction time.

My problem is that in the keyboard-response, the duration is "keypress". That means the stimulus disappear after the participant gives is answer. So, the presentation time of each stimuli change according the reaction time.

What I want is to have the same presentation time for each stimuli (1000ms).

Here is my code :

Sketchpad :

set duration 0
set description "Displays stimuli"
draw textline center=1 color="[Color_word]" font_bold=yes font_family=mono font_italic=no font_size=32 html=yes show_if=always text="[Word]" x=0 y=0 z_index=0

Keyboard_response :

set timeout 3000
set flush "yes"
set duration "keypress"
set description "Collects keyboard responses"
set correct_response "[Correct_response]"
set allowed_responses "q;s;l;m"

I tried to set duration in keyboard response as "1000" ms but it crashes (the task doesn't run).

Can somebody help me with this error ?

Thank you very much !

Céline

sebastiaan · January 2016

Hi Céline,

This sounds like a situation for the coroutines plug-in, which is described here (and needs to be installed separately):

http://osdoc.cogsci.nl/usage/coroutines/

Essentially, you want to do two things simultaneously:

Collect a keyboard response with a timeout of 3000 ms; and
Show a target sketchpad, followed by a blank sketchpad 1000 ms later.

In the coroutines plug-in, this would look as follows:

Does that make sense?

Cheers,
Sebastiaan

vvogel · January 2018

I had a similar problem and used your solution:

instead of a "sequence" I added a "coroutine" but now I always get an error message!

File "C:\Program Files (x86)\OpenSesame\lib\site-packages\libopensesame\item.py", line 235, in getattr
raise AttributeError(u'%s not found' % var)
AttributeError: canvas not found

I really don't get the problem. What did I do wrong?

Thanks in advance

sebastiaan · January 2018

@vvogel Until recently there was a bug with feedback items within a coroutines. So that's what you're running into. I would either:

Use sketchpad items instead of feedback items; or
Grab the latest (soon-to-be released) OpenSesame 3.2 prerelease from http://osdoc.cogsci.nl/3.2

Cheers!
Sebastiaan

Anna_Schellhorn · March 2022

Hi Sebastiaan,

I have a problem related to the topic here. I also want to present visual stimuli for a certain time and at the same time capture the reaction time measured by a keypress. I already tried to use Corountines, but in the files only the duration of the keypress itself appears, I guess, because it is always around 0.5-0.7 ms. So how is it possible to capture the time between the start of the stimulus presentation and the following keypress?

Thank you!

Anna

sebastiaan · March 2022

Hi @Anna_Schellhorn ,

The response_time always reflects the interval between the start of the keyboard_response and the moment that a key was actually pressed. If you're using a coroutines item, this means that the start time of the keyboard_response (in the coroutines ) should coincide with the start time of the sketchpad (in the coroutines ) that contains the stimulus. Does that clear things up?

— Sebastiaan

Anna_Schellhorn · March 2022

Hi Sebastiaan,

thank you for your answer. So, the response time reflects the interval between the start time of the visual stimuli and the actual keypress and so, if i pressed the key always after approximately 5 seconds the response_time should display something around 5000ms, but in the excel file the response_time_keyboard_response displays values around 0.5(ms) and I don't understand why that is. Could you comment on that again?

Thanks again,

Anna

sebastiaan · March 2022

Hi @Anna_Schellhorn ,

Without knowing the details of how you implemented the experiment, this is impossible to say. Could you attach the experiment file here?

— Sebastiaan

Anna_Schellhorn · March 2022

Hi Sebastiaan,

of course. Attached you should find the Example experiment file.

Anna

Anna_Schellhorn · March 2022

Hi Sebastiaan,

sorry, apparently it didn't work to attach the open sesame file. Attached you can find now some screenshots, which should demonstrate the implemented experiment.

Bildschirmfoto 2022-03-23 um 14.37.45.png

Bildschirmfoto 2022-03-23 um 14.39.19.png

Bildschirmfoto 2022-03-23 um 14.39.27.png

sebastiaan · March 2022

@Anna_Schellhorn The start and the end time of the keyboard_response are both set to 0. So this means that key presses are only polled once, at the very start of the coroutines . If you to poll continuously, then you have to set the end time to 9995 (in your case, i.e. the duration of the coroutines ). Does that clear things up?

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