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<body>Hello Scott,<BR>
<BR>one way of doing this is the following (I assume you already have a simple script for displaying the stimuli):<BR>
<BR>
Add the following declarations to the gloabal user script (menu-view-script-user tab):<BR>
<BR>
<FONT face="Courier New, Courier, Monospace">Const ExposureDelta% = 1000<BR>Const ExposureLowLimit% = 1000<BR>Const ExposureHighLimit% = 20000</FONT><BR>
<FONT face="Courier New, Courier, Monospace">dim iExposureTime as long<BR>dim strPrevResp as string</FONT><BR>
<BR>Then, insert an inline script object to initialize the global iExposureTime variable (this would normally be at the start of a block):<BR>
<BR>
<FONT face="Courier New, Courier, Monospace">iExposureTime = 8000</FONT><BR><BR>
Then, insert an inline script just before the image object (called Stim in this example) to set the exposure time of the simulus object:<BR>
<BR><FONT face="Courier New, Courier, Monospace">Stim.Duration = iExposureTime</FONT><BR>
<BR>
Finally, insert an inline script after the stimulus object to check the response and modify the exposure time:<BR>
<BR>
<FONT face="Courier New, Courier, Monospace">' get the response</FONT><BR>
<FONT face="Courier New, Courier, Monospace">Dim t as string<BR>t = LCase$(Stim.RESP)</FONT><BR>
<FONT face="Courier New"></FONT> <BR>
<FONT face="Courier New">' check response and alternation</FONT><BR>
<FONT face="Courier New, Courier, Monospace">if t="n" And strPrevResp<>"n" Or t="m" And strPrevResp<>"m" then<BR> iExposureTime = iExposureTime + ExposureDelta<BR>elseif t="z" And strPrevResp<>"z" Or t="x" And strPrevResp<>"x" then<BR> iExposureTime = iExposureTime - ExposureDelta<BR>end if</FONT><BR>
<FONT face="Courier New"></FONT> <BR>
<FONT face="Courier New">'check upper and lower limits</FONT><BR>
<FONT face="Courier New, Courier, Monospace">if iExposureTime<ExposureLowLimit then<BR> iExposureTime = ExposureLowLimit<BR>elseif iExposureTime>ExposureHighLimit then<BR> iExposureTime = ExposureHighLimit<BR>end if</FONT><BR>
<FONT face="Courier New"></FONT> <BR>
<FONT face="Courier New">' remember the response to check for alternation</FONT><BR>
<FONT face="Courier New, Courier, Monospace">strPrevResp = t</FONT><BR>
<BR>
You might consider removing the alternation test (and related code) and only use two keys because eprime will not generate repeating key presses when the key is hold-down. (Authorware will!) <BR>
<BR>
Hope this helps,<BR>
<BR>
Paul Groot<BR>
VU University, Amsterdam<BR>
<BR> <BR>
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<BR>
> Date: Fri, 20 Apr 2007 11:22:48 -0400<BR>> From: smoeller@umich.edu<BR>> To: eprime@mail.talkbank.org<BR>> Subject: varying lengths of exposure based on responses<BR>> <BR>> Dear Colleagues,<BR>> <BR>> I'm fairly new to using e-prime, and I'm hoping someone can help me out <BR>> with a question.<BR>> <BR>> A somewhat recent paper (Aharon et al., 2001) describes a task in which <BR>> participants are exposed to faces. The catch is that participants <BR>> could vary the amount of exposure they had to these faces by their <BR>> responses. The default length of exposure was 8s. If they wanted the <BR>> faces to disappear faster, they could alternate pressing the "z" and <BR>> "x" keys. However, if they wanted the pictures to remain on the screen <BR>> for longer than 8s, they could alternate pressing the "n" and "m" keys.<BR>> <BR>> The authors used Authorware (Macromedia) for this task. I was <BR>> wondering if a similar task could be performed using e-prime.<BR>> <BR>> Thank you for your time!<BR>> <BR>> Best regards,<BR>> <BR>> Scott Moeller<BR>> University of Michigan<BR>> <BR><BR><br /><hr />In 2 tellen een webpagina voor al je fotos makkelijk en gratis met Windows Live Spaces <a href='http://clk.atdmt.com/MSN/go/msnnksac0030000001msn/direct/01/?href=http://www.imagine-msn.com/spaces' target='_new'>Windows Live Spaces</a></body>
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