psychopy.org | Reference | Downloads | Github

Response key error


#1

OS (Win10) (also on Win 7):
PsychoPy version** (1.90.3):
Standard Standalone

I’m new to psychopy and am creating a simple experiment. It’s a selective attention task that shows one of three stimuli (T, X, or C) in a fixed order. The start time of each stimuli is defined in my conditions file as $stimtime, a column of random numbers between 0.55 and 2.25.

The objective is to push the down key when the X stimulus appears.
Here’s how I initially put the response key. I tried all the different options in ‘Store’.

When I run my experiment, after the instructions, the first stimulus shows appears, but nothing after that. The screen just remains grey and doesn’t present the rest of my stimuli.

I went into the response, and entered a duration of 0.7 seconds, and that fixed the problem. All of my stimuli appeared in order as they should. But, then a problem with the data came about. For every response, it would show the response as one stimulus after than the response actually occurred. Giving an incorrect response both for the X and the following T. I did it multiple times and had other people do it to make sure I wasn’t just responding slowly.

Also, if I remove the response key entirely, the task runs fine (besides not being able to respond) and all the stimuli appear.

I’m lost at this point so any help would be greatly appreciate!


#2

Some of this doesn’t really make sense. Can you provide a screenshot of your flow panel?

Also, if you are using any custom code in code components, please provide it.

Lastly, note that you have too much resolution in your stimtime variable. It should be rounded to fit the granularity of the refresh rate of your monitor (or perhaps even better, define it in terms of a number of frames rather than a duration in time).


#3

Hi Michael,

Thanks for the advice, changing it to frames is a really good idea, I need precision in timing. But even with that I’m still running into the same problem. In the response (keyboard), if I leave the duration blank, then when I run it, the first stimulus appears but nothing after that. If I put anything in the duration, all the stimuli appear as they should, but the response in the data spreadsheet is marked at occurring one stimulus after it actually happened (shown by the two 0s in a row in the K column in my last post.

Here’s a screenshot of the overall flow (with a blank duration of response) and my stimulus.


Also, if this helps, attached is my experiment and conditions file. Lastly, I do not have any custom code.

oddball task.psyexp (16.5 KB)

Conditions.xlsx (10.0 KB)