Millisecond Forums

+x

 

kev_dent - 12/6/2023

Hi,

I would like to create an experiment where participants view images.
I would like to be able to have a participant increase or decrease the amount of time the stimulus is shown to them for by pressing keys.
Press one key to increase the stimulus duration, press another key to decrease it.
What would be the best way to implement this with inquisit?

Thanks
Kevin

+x

 

kev_dent - 12/6/2023

Let me try that again.

Default duration of the stimulus is 4000ms if the participant presses z every press of z adds 100 ms on to this time.
If the participant presses n every press of n decreases the stimulus duration by 100 milliseconds.
The keypresses should occur whilst the stimulus is on the screen.
The sequence of keypresses and their timing relative to the start of the trial should also be recorded.
Thanks
Kevin

<trial t>
/ stimulustimes = [0=t]
/ beginresponsetime = 0
/ inputdevice = keyboard
/ validresponse = (44,49)
/ responseinterrupt = trial
/ isvalidresponse = [
  if(trial.t.response == 44) {trial.t.trialduration = trial.t.trialduration + 100; false} else if
(trial.t.response == 49) {trial.t.trialduration = trial.t.trialduration - 100;false}
]
/trialduration = 4000
</trial>


<text t>
/items =("X")
/ erase = false
</text>

+x

 

Dave - 12/6/2023

+x

 

kev_dent - 12/6/2023

Let me try that again.

Default duration of the stimulus is 4000ms if the participant presses z every press of z adds 100 ms on to this time.
If the participant presses n every press of n decreases the stimulus duration by 100 milliseconds.
The keypresses should occur whilst the stimulus is on the screen.
The sequence of keypresses and their timing relative to the start of the trial should also be recorded.
Thanks
Kevin

<trial t>
/ stimulustimes = [0=t]
/ beginresponsetime = 0
/ inputdevice = keyboard
/ validresponse = (44,49)
/ responseinterrupt = trial
/ isvalidresponse = [
  if(trial.t.response == 44) {trial.t.trialduration = trial.t.trialduration + 100; false} else if
(trial.t.response == 49) {trial.t.trialduration = trial.t.trialduration - 100;false}
]
/trialduration = 4000
</trial>


<text t>
/items =("X")
/ erase = false
</text>

Actually, scratch what I posted previously. It won't work reliably that way. The fundamental problem is that a trial's duration really isn't meant to be changed once it's underway, for obvious performance and timing reasons. So, back to the drawing board. Not sure this can be done, or done well, i.e. without incurring serious timing hiccups