Preventing keyboard response from ending trial / Fixed SOA regardless of response timing

Fab · March 2021

Hi there,

This is probably a very naive question and something I should have been able to find out by myself, but I'm stuck... I have a task in which I'm presenting a fixation cross (200 ms), followed by a sound (200 ms) , followed by a target stimulus (200ms) followed by the fixation cross during a response window of maximum 1300 ms. At the moment, I've set up the latter fixation cross display to a duration of 0 ms, and I then have a keyboard response object with a time out of 1295 ms.

However, there are two things I'd like to achieve

(1) I'd like to measure RTs from the onset of the target sketchpad instead of the onset of the second fixation cross display (post_target_interval)

(2) I'd like the inter-trials interval to be fixed, that is, I'd like the post_target_interval to remain visible even after the response has been registered (i.e., that the response does not end the post_target_interval). Alternatively, I thought of creating a "post_response" sketchpad and set its duration dynamically to, say, 1300 ms minus the response time in the current trial, but haven't managed to do so.

Importantly, if code is required, it should be javascript code, 'cause I'd like to be able to run the experiment online as a JATOS experiment.

Any suggestion greatly appreciated! Thanks in advance!

Fabrice.