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Forum Newbie
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Last Login: 6/27/2008 4:26:35 PM
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| Could someone please help me figure out how I can flash a stimulus text on a screen for x ms, and allow the subject y ms to respond, where y > x? I have tried setting Duration to x, Time Limit to y, and EndAction to Terminate, but it appears that the modus operandi is: Display stimulus for Duration, unless first interrupted by a response. Response is only considered/detected if it happens w/in TimeLimit or Duration, which ever is shorter. Thanks.
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Forum Guru
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Last Login: Yesterday @ 5:08:57 PM
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You need to set End Action to (none).
-- David McFarlane, Professional Faultfinder
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Forum Newbie
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Last Login: 6/27/2008 4:26:35 PM
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Visits: 7
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| Thanks for your reply. I need to clarify my question: I want a text to display for 500ms only. The response will be considered correct if the subject presses button 1 within 1200ms of the stimulus onset (text presentation). I put a Wait function of 700ms after the text display, so that the subject is seeing a blank screen even while he/she is allowed to respond w/ a button press. The problem is that if the subject responds 0-500ms post-stimulus, the response is registered and counted as correct, but if he/she responds between 500 and 1200 ms post-stimulus, it is not detected and considered incorrect.... The strange thing is I tried allowing a spacebar response, and that works fine (i.e., Response.ACC = 1 even when Response.RT > 500ms and less than 1200ms), but not with the PST Serial Response Box. (And it does register just fine if the subject responds within 500 ms). Thanks again.
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Forum Guru
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Last Login: Yesterday @ 5:08:57 PM
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D Won (6/27/2008)
I want a text to display for 500ms only. The response will be considered correct if the subject presses button 1 within 1200ms of the stimulusonset (text presentation).
I put a Wait function of 700ms after the text display, so that the subject is seeing a blank screen even while he/she is allowed to respond w/ a button press.
The problem is that if the subject responds 0-500ms post-stimulus, the response is registered and counted as correct, but if he/she respondsbetween 500 and 1200 ms post-stimulus, it is not detected and considered incorrect....
If I understand, you have a text object (let's call it ProbeText) that accepts input while it is displayed for 500ms, it then clears itself (i.e., ClearAfter = Yes), then a wait object (let's call it MaskWait) accepts input for its duration of 700ms.
This is exactly how almost everyone first tries to allow an input duration longer than a display duration. But E-Prime has a better way, which is covered in Appendix C of the User's Guide, in the section on "Basic Reaction Time: Extended Input". First, do not (repeat, do not) accept any input for MaskWait. Instead, set the input mask Time Limit of ProbeText to 1200ms. Now ProbeText will display for 500ms, but it will continue to accept a response for the full 1200ms, and E-Prime will treat any response as coming from ProbeText. It's that simple.
The strange thing is I tried allowing a spacebar response, and that works fine (i.e., Response.ACC = 1 even when Response.RT > 500ms and less than 1200ms), but not with the PST Serial Response Box. (And it doesregister justfine if the subject responds within 500 ms).
Now it sounds like ProbeText has two input masks, one for SRBox and one for keyboard. Note that the input mask properties need to be set separately for each allowed input mask: Click on SRBox and set those properties as needed, then click Keyboard and set those as needed. I suspect someone already set the input mask for the Keyboard with a Time Limit of 1200ms, but the SRBox Time Limit is set to only 500ms.
-- David McFarlane, Professional Faultfinder
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