E-Prime data file

[David Vinson]

Hi Hank,

We have experienced something very similar in experiments with 
contingent designs (skipping one or more data collection objects 
depending on various characteristics of responses).

I'm sure someone else has a more elegant solution but we got around this 
problem by adding inline code which set these variables to impossible 
values (e.g. RT = -99) if a particular object was not run on a given 
trial. Then we filtered such values out of any analyses we conducted.

cheers,
david

On 02/12/2011 14:44, Hank Jedema wrote:
> Hi All,
>
> Here is something in the E-data file that seems problematic and
> puzzles me: In a stoptask I use a number of if - then scripts to
> present a sequence of stimulus slides. The script occurs just after
> each slide and dependent on the whether a response was received or
> that the slide simply timed out (i.e. reached the end of its slide
> duration), the script will advance the trial on to the next slide
> (let's say slide B if a response was received or slide C if no
> response was received. The issue that I am having is that when I log
> the response and onset time etc for slides B and C, the E-data file
> list values for all, even though the slide B and C are mutually
> exclusive. I would expect a "NULL" for the slide that was not
> presented, but instead if slide B was actually presented, it will list
> the values from a prior trial for slide C duration, slide C response
> etc, and vice versa. The program is is structured so that 2 nested
> lists specify the trial type and stimulus duration and the program
> properly runs the correct number of trials (300). In the E-data file
> each trial provides one line of data. What am I missing? Thanks very
> much for your help.
> Hank
>

-- 
David Vinson, Ph.D.
Senior Postdoctoral Researcher
Cognitive, Perceptual and Brain Sciences Research Department
University College London
26 Bedford Way, London WC1H 0AP
Tel +44 (0)20 7679 5311  (UCL internal ext. 25311)


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