Correcting RTs for positive SOAs (picture word interference)

[Susan Campbell]

It is possible to correct the RT immediately after the response each time,
and it appears to be relatively straightforward.

After the Wait object is presented, you could do the following in an
Inline:
Get the SOA
If the SOA is positive,
Wait.RT = Wait.RT + SOA

For an example of something similar, you can look at the script from
http://step.psy.cmu.edu/scripts/Attention/Pashler1992.html

Hope this helps,
Susan Campbell
STEP Project
Carnegie Mellon

On Mon, 25 Nov 2002, David Vinson wrote:

> Hello all,
>
> I am wondering if anyone can help me out with a small design problem.  We
> are carrying out a picture-word interference experiment, and are
> manipulating SOA between the picture and word displayed.  We always want to
> measure RT from the picture onset.
>
> If SOA < 0, the word is displayed before the picture, if SOA > 0, the word
> is displayed after the picture.  We currently use conditional branching to
> determine the order in which these items are displayed, and collect RTs
> from an empty "Wait" object that immediately follows the last-presented object:
>
> (SOA < 0)
> Word display for [-SOA] milliseconds
> Picture display
> "Wait" object until response is made
>
> (SOA > 0)
> Picture display for [SOA] milliseconds
> Word display
> "Wait" object until response is made
>
> The problem is in the latter condition: RTs measured for the "Wait" object
> underestimate the picture response latencies by (SOA) milliseconds.  Is
> there a way to automatically correct these RTs in the datafile using an
> inline object?  Or alternatively, is there an easy way to create a new
> variable (e.g. CorrectedRT) which is logged to the datafile?
>
> Thanks,
> David Vinson
> Dept of Psychology, University College London
>
>
>
>