Negative Reaction Time

OS:MacOS - latest
PsychoPy version: V2022.2.5, latest, 3.1.2, 2023 (my “stable” is on V2022.2.5, but I’ve tried the others based on other people’s forum posts)
Standard Standalone? (y/n) If not then what?: y

What are you trying to achieve?:
Participants should see an ITI fixation cross on the screen for 1-1.5 seconds, then be presented with the stimuli (text - numbers 1-9) for 3 seconds, they are to press P/Q to indicate correct/incorrect match (2-back paradigm).

What is happening however, is that the reaction time recorded for the P/Q response can be negative (i.e., recorded during the ITI presentation), and the 3 second keyboard recording window is actually 3 minus the ITI time, even though the stimuli number is still on the screen for a full 3 seconds.

What did you try to make it work?:

  • Tried $iti.status==FINISHED (doesn’t work, incorrect media, simply throws an error as our ITI is a code snippet and the cross that is paired with it is text stimuli)

  • Tried starting the keyboard response to be when the text stimuli is presented and all other possible duration/time/condition combinations, none of them work. They all continue with negative times, no keyboard recording at all, or positive numbers - but these numbers are recorded during the ITI.


do you mind showing us the relevant experiment flow?

Best wishes Jens