Image display delay

[元 杨]

Dear David

        I have read Chapter 3 of Userguide thoroughly, but still feel a little confusion. In each block of my programme, there was a TextDisplay, a Inline Scripe and a ImageDisplay(stimulous).To synchronize the signal of NeroScan and the stimuli of e-Prime, I have inverted a in-line WritePort command before "ImageDisplay" and set the PreRelease time (100ms) in the TextDisplay. However, the unwanted delay or unsynchronization still existed between the e-Prime and EEG recording system result in anormal delay of N170 component. Thus, I want to ask whether the WritePort command was sent to the recording system at the beginning of Prelease time or at the point when stimulous presents on the screen. In other word, I want to know whether the WritePort command and image were sent at the same time from E-Prime.

      Thank you for your concerning.

                                                                                                                       
> Date: Wed, 8 Apr 2009 11:26:12 -0400
> To: e-prime at googlegroups.com
> From: mcfarla9 at msu.edu
> Subject: Re: Image display delay
> 
> 
> At 4/5/2009 09:35 PM Sunday, maocong wrote:
> >I am a greenhand in programming on e-prime, and I need some help on
> >the fellowing issue:
> >
> >I designed an ERP visual stimulous experiment by using the control of
> >ImageDisplay on e-Prime 2.0v and the EEG recording system is NeroScan
> >4.3v. And I found a 8~14ms delay on image display(shown by the
> >programme running result file), and the help file showed this delay is
> >the difference between orignial onset time and actual display time.
> >This random image display delay greatly effect the accuracy of N170
> >latency recorded, which lead to the unreliablity of the experiment
> >result. Therefore I hope you can give me some advices about how to
> >eliminate/compensate this display delay or how to uniform this display
> >delay
> 
> Please read thoroughly chapter 3 ("Critical timing...") of the User's 
> Guide that came with E-Prime.
> 
> -- David McFarlane, Professional Faultfinder
> 
> 
> > 

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