critical timing (working with prerelease and event timing)

[Jim]

Namaste David,

Thanks, I'll reply in the other post.

Jim

On Feb 22, 5:54 pm, David McFarlane <mcfar... at msu.edu> wrote:
> Jim,
>
> Please see my comments in your thread, "scoring a nonresponse as a
> correct answer".
>
> (OK, now I'm late for my yoga class, and I really need the exercise.)
>
> -- David McFarlane, Professional Faultfinder
>
>
>
> >Hello forum,
>
> >I sent this question to e-prime support last week; unfortunately, they
> >are experiencing high volume and have been taking a long time to get
> >back to my requests. They are time sensitive, so I was hoping the
> >forum might have some ideas.
>
> >I was sent an e-prime task, and I will be using it in conjunction with
> >a physiological data collection system. I have figured out how to send
> >TTL pulses from e-prime to the physio system, and have the physio data
> >collection starting with a pulse from each block of the task. However,
> >there is no way to offset the physio data collection with a pulse, so
> >the offset of the physio data collection is specified by a user-
> >defined duration.
>
> >The problem I am running into is that each block of my task does not
> >end at the same time each time I run it. After reading the critical
> >timing chapter of the e-prime manual, I understand now why this is the
> >case (at least in part). However, I am not sure how to fix this
> >problem for my particular task. Presently there is no prerelease
> >specified and all objects are set to event timing mode; I have
> >questions about both of these options as they relate to this specific
> >task:
>
> >Prerelease: The task consists of several blocks, and within each block
> >is a repeating sequence of events; a stimulus is shown for 3 seconds,
> >the participant responds during that interval and is given on screen
> >feedback as an overlay on the stimulus screen (the latency of the
> >feedback presentation is contingent upon participants' response;
> >regardless of participants' response the stimulus is displayed for 3
> >seconds), then there is a 500ms blank screen. After reading the
> >critical timing chapter, I got the impression that one should not use
> >prerelease on sequences including feedback. I get the sense that I may
> >be able to have prerelease on some objects but not others, but it is
> >very important that the data logging and feedback are correct for the
> >task, so I am reluctant to use prerelease on anything. Thoughts?
>
> >Event timing: Although I understand the difference between cumulative
> >and event timing, I am still having a hard time grasping the
> >implications of using each for my experiment; in particular I am not
> >sure how each choice would impact data analysis. E-prime will be
> >sending pulses to the physio machine that onset and offset with the
> >onset and offset of each stimulus. I want to be able to look at
> >physiological response to the stimuli (so it's an "event-related"
> >design). Given my question, I'm not sure about the relative pros and
> >cons of event and cumulative timing and what impact that decision will
> >have on my attempts to analyze the data. I am reluctant to change it
> >to cumulative timing because the task was made with "event timing"
> >set. Again, it seems like here too it might be best to use event
> >timing on certain objects and cumulative timing on others, but I'm not
> >sure what impact this would actually have on the experiment or which
> >objects to use what timing on.
>
> >Thank you so much for your help
> >Jim- Hide quoted text -
>
> - Show quoted text -

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