[DMDX] Re: question about timing in a fMRI experiment I guess it depends on what you mean by "radically different" First, remember that this is my notebook at home which may not be ideal for running DMDX.  However, we are observing the same problems on desktops configured for DMDX on campus. When I do "Basic Tests: Refresh rate" it returns either 16.64 or 16.66.  Currently 16.661 is saved in the registry from the last timing test. If I use 16.661 and press the Enh Retrace button in the Time Video mode test, I see a blue box in center of screen with red on top and bottom.  Its fairly stable with a little jumping up and down but no systematic movement of the boxes in either direction.  If I use 16.641 and press the Enh Retrace button, the red and blue boxes slowly scroll up the screen, suggesting this isnt the right setting?  Therefore we have continued to use 16.661 If I select the Do Test button from Time Video mode, I get relatively high timed out retraces (53%) and multiple misses (19%) but 0% certain errors. If I run the Tachistoscopic Acid test for 141 flips, I get 140 timed out, 0 multipy timedout 0 certain errors, 0 last minute flips, 0 wait for blit, the longest flip is 16.86 and the longest blit is 17.69. Do any of these stats suggest the source of the error?  Its surprising to me that it occurs on multiple computers also. J On 8/7/05, j.c.f.  wrote: > At 12:48 PM 8/7/2005 -0500, you wrote: >  > >JUST TO BE CLEAR, THE LONG DELAYS WERE NOT DETERMINED SOLELY BASED ON > >TIME NEED TO PRESENT THE BMPS.  WE ADDED EXTRA TIME TO THE DELAYS FOR > >TIMING ISSUES RELATED TO THE TASK.  ITS NOT A PARTICULARLY OLD OR SLOW > >COMPUTER AND WE COULD HAVE USED SHORTER DELAYS IF NEEDED. >  >   Doesn't matter, you need to check the preparation times.  The fastest > machine in the world can be reduced to slow pig by worms or a failing hard > disk.  But from the results below I'd say that's not your problem as we'd > be seeing display errors. >  >  > >YOU MENTION COMMENTS AS A POSSIBLE SOURCE OF THE PROBLEM.  I WOULD > >HAVE ASSUMED THAT TEXT THAT IS COMMENTED OUT WAS DISCARDED PRIOR TO > >RUNTIME WHEN DMDX PARSED THE ITEM FILE. >  >   No, it's an item that's ignored but it's still an item and the delay > parameter affects it and so comments are a concern when D is 1. >  >  >  > > d60 f1        >800,600,600,16,60>   > >0   "Press SPACE to BEGIN"; > >+11   *  "blue" <% 20>  /; > >+11   *  "blue" <% 20>  /; > >+11   *  "blue" <% 20>  /; > >+11   *  "blue" <% 20>  /; > >+11   *  "blue" <% 20>  /; > >+11   *  "blue" <% 20>  /; > >+11   *  "blue" <% 20>  /; > >100000  "the end"; > > > >******************* > >The Zil File output > >******************* > > > >Subjects incorporated to date: 002 > >Data file started on machine EVO > > > >********************************************************************** > >Subject 1, 08/07/2005 12:44:51 on EVO, refresh 16.66ms, ID 1       COT > >Item 11, COT 0.00, No Responses. > >Item 11, COT 1349.56, No Responses. > >Item 11, COT 2682.45, No Responses. > >Item 11, COT 4032.01, No Responses. > >Item 11, COT 5364.90, No Responses. > >Item 11, COT 6697.79, No Responses. > >Item 11, COT 8030.69, No Responses. > > > >********************************************************************** > >Subject 2, 08/07/2005 12:45:13 on EVO, refresh 16.66ms, ID 2       COT > >Item 11, COT 0.00, No Responses. > >Item 11, COT 1349.55, No Responses. > >Item 11, COT 2699.11, No Responses. > >Item 11, COT 4048.66, No Responses. > >Item 11, COT 5381.56, No Responses. > >Item 11, COT 6731.12, No Responses. > >Item 11, COT 8080.68, No Responses. >  >  >    Well I'd be checking TimeDX's values for that display mode, what you > see there with an item taking 80 or 81 ticks when it should be taking 81 > ticks pretty much only comes about when the retrace interval is radically > different than that which is described in the registry.  I'd be seeing if > the Enhanced Retrace Test really indicates a 60 Hz retrace and not > something else entirely. >  >                                                /"\\ >  -jonathan (j.c.f.)                            \\ / >                                                 X >     ASCII RIBBON CAMPAIGN - AGAINST HTML MAIL  / \\ >  >   People with narrow minds usually have broad tongues >  >  > ==================================================================== >   Send mail to DMDX-request@psy1.psych.arizona.edu with the word >  'unsubscribe' by itself with no quotes in the body of the email >  to be removed from the list.  The list archive is available here: >          http://psy1.psych.arizona.edu/cgi-bin/DMDX/thread > ==================================================================== >  --  John J. Curtin, Ph.D.  Assistant Professor of Psychology  University of Wisconsin  1202 West Johnson St.  Madison, WI 53706  Email: jjcurtin@wisc.edu  Website: http://dionysus.psych.wisc.edu Office: 608-262-0387  Lab: 608-262-5621  Cell: 608-217-6221  Fax: 608-262-4029