[solved] setting a variable delay in advanced_delay so as consistent trial lengths

JoshuaBaker

i am wanting to keep all trials the same duration. On trials where a response is given, I define a variable 'wait', as

exp.set('wait', round(1000 - exp.get('response_time_keyboard_response'))

where 1000 is a typical trial length when no response is given. I then type in duration '[wait]' in the advanced delay script. I am logging the variable 'time_fixation_dot' (which appears first in the sequence) and calculating how long each trial is. The delay is not working. I am printing exp.get('wait') which looks correct in the debug window. looking in the logfile, however, trials are not the same length. when a keypress is given, the trial jumps ahead straight to the fixation dot again, but not always..

Please advise!

Josh

Hi Joshua,

Based on this information I'm not sure what causes your problem. Are you sure the wait variable is assigned a value under all circumstances? Does the line of code where you create wait appear after the part that collects a keyboard response? Otherwise wait would be calculated with the response time from the previous trial..

If your keyboard response is collected with an inline_script, you could also add the simple line self.sleep(1000 - response_time_keyboard_response), that will get you to 1000ms as well.

Cheers,

Josh

JoshuaBaker

Thanks Josh. Everything is in the correct place, it just decided not to work I've had success with doing it before, but for some reason it no longer works. Ideally I would have a blank screen presented for the variable duration and so a self.sleep within a key response code would not satisfy this as I wish for all stimuli to immediately leave the screen on a keypress, and then a variable delay.

JoshuaBaker

problem solved! I didn't even bother having a 'wait' variable. I simply presented a blank sketchpad with a zero duration and had an inline script after it containing.

self.sleep(3000-exp.get('response_time_keyboard_response')).

looking at the log for time_fixation, all trails are now the same duration. Thanks for the self.sleep idea

Joshua