Set the timing to record RT?

Peter Quain pquain at une.edu.au
Wed Sep 16 05:04:45 UTC 2009


You say you're new to e-prime. Using dummy object, something like 
this in an inline before the end of a trial would log true RT from 
sound offset:

dumOnset = c.GetAttrib("dummy.OnsetTime")
dumRT = c.GetAttrib("dummy.RT")
soundOffset = c.GetAttrib("soundObject.OffsetTime")
adjustRT = soundOffset - dumOnset
realRT = dumRT - adjustRT
c.SetAttrib "ReactionTime",  realRT

maybe something like this would work (or maybe not..): use 'dummy' 
object (a text object, duration = 0, wait for response = forever; 
response action = jump to label) just before sound object, to collect 
RT. There is a sample experiment on e-prime samples which illustrates 
this, maybe someone remembers its name? Is it CollectInputDuringInLine?

Log onset time of dummy. Log offset time of sound object. Compute 
adjustRT = sound offset - dummy onset. After RT is collected, compute 
realRT = dummy.RT - adjustRT . Set realRT as attribute.

At 02:01 PM 16/09/2009, you wrote:

>Dear all,
>
>I'm still a rookie in E-Prime and designing an ABX discrimination
>task. I got a question about the timing to record RT. Does anyone know
>how to set the timing to record RT in E-Studio 2.0? I looked up the
>user's guide and it says that RT is always recorded from the onset of
>the response logging event. However, this is not the way I want. I
>need to record RT right AFTER subject has heard the audio stimuli. I
>tried two different methods, but none of them gave me accurate RTs.
>
>The first thing I tried was making the sound object itself as the
>response logging event, but in that case, RT would be measured from
>the onset of the event, which was BEFORE the whole sound file has been
>played to the subject and the RT would include the duration of the
>sound "file", which was way longer than subject's actual response.
>
>The second thing I tried was adding a "Wait" object which records RT
>AFTER the sound object. The duration of the sound object was set to
>1500ms, but given that the length of sound files were all different,
>the wait object didn't immediately start right after the sound "file"
>was played. Rather, the wait object started after the whole 1500ms of
>sound object had elapsed. Now the problem is that subject may already
>start responding before the whole 1500ms has elapsed, so some parts of
>RT will be missing since subject starts responding before the wait
>object which records RT starts. So, does anyone have any idea to
>record RT right after the sound "file" has been played to the
>subject?
>
>Thank you in advance for your great help!!
>
>-Martin
>

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