problem with extended response collection (also "the virtue of collecting multiple responses")

Tobias tobias.fw at gmail.com
Fri Feb 11 14:39:32 UTC 2011


Hi again,

I think I still have a problem understanding the advantage or the
principle itself of your suggestion. If I have the Slide1 for 250 ms,
"infinite" as the time limit and end action "terminate" (as you
suggested if I understood you correctly), it is still collecting data
after offset of the Slide1 oder the ExtendedStim. I mean in both cases
Slide1 will collect data until a first button press is recognized. In
both cases, if Slide1.resp is collected, the response screen should
not appear. And for the responseSlide, if I don't specify the response
collection, it will stay on the screen forever (I tried it).

Maybe we talk at cross purposes? Don't know...

BEst,
Tobias

On 11 Feb., 13:08, Michiel Spape <Michiel.Sp... at nottingham.ac.uk>
wrote:
> Hi Tobias & List,
> It seems the "infinite duration until response and stimulus disappears as a result" thing, which is so much easier to do in E-Prime than anything else, seems to become less popular as people are more often using neuroscience weaponry these days. A minimum duration property would be quite nice, but is pretty much lacking. Anyway:
> - no, there should be no flicker, unless you set the clear-after property to true (which it isn't by default). As long as both slides look identical, that is. The timing-wise difference is not so much in the interval in between as the stimulus keeps collecting data between the two objects (asynchronously, if you like). I would say, try it, see if it works better. If not, there's at least less code involved and it saves some redundancy in the data collection here (which seems, as you say, to work out well enough). I might be missing something here, I'm not very good at debugging without seeing it happening in E-Prime.
>
> As an aside, I find it - especially while doing EEG - quite often very useful to
> - have a response-collecting object with some time limit started long before any stimulus. It's very easy to code, afterwards, something like
> c.SetAttrib "Y_RT", myResponseCollectingObject.RTTime - myStimulusObject.OnsetTime
> - have it collect multiple responses, then afterwards (or in your case, both in the middle and afterwards) sorting these out (code for that is in this e-prime list somewhere). Crucially, and I never thought of this until two years ago when I started doing bimanual experiments, in almost any single-response experiment, there is a good chance a participant will react A THEN SWITCH to B as he/she changes his/her mind. If A was actually the correct answer, you'd usually (or at least, by e-prime default) incorrectly classify the whole bit as a correct response. "Incorrectly" might be debatable, but I find it safer to throw out all dual-response data (if the correct answer is a single response). I should point this out in the e-Primer :)
>
> Best,
> Mich
>
> Michiel Spapé
> Research Fellow
> Perception & Action group
> University of Nottingham
> School of Psychologywww.cognitology.eu
>
> -----Original Message-----
> From: e-prime at googlegroups.com [mailto:e-prime at googlegroups.com] On Behalf Of Tobias
> Sent: 11 February 2011 11:25
> To: E-Prime
> Subject: Re: problem with extended response collection
>
> Hi Michiel,
>
> thanks for your reply. Indeed I am using EEG and the search/stimulus
> slide should be equally long presented in each trial and for each
> subject. The trick with the subtraction of "Slide1.Duration" is a good
> idea, I will try that later. But isn't there a flickering or something
> between Slide1 and ExtendedStim? Anyway, I am not sure if your
> suggestion makes a difference timing-wise: Between ExtendedStim and
> ResponseSlide is the same number of microseconds, milliseconds or
> whatever than in my former version between Slide1 and ResponseSlide.
>
> One more thing about the response collection: The result file shows
> that Slide1.RESP has a value no matter when the subject responds and
> no matter if the ResponseSlide is already shown. If the subject
> responds during ResponseSlide, Slide1.RESP and ResponseSlide.RESP have
> the same value, namely the key the subject pressed.
>
> Best,
> Tobias
>
> On Feb 11, 11:11 am, Michiel Spape <Michiel.Sp... at nottingham.ac.uk>
> wrote:
> > Hi,
> > If you're right (and I guess it is possible), then you might try setting offset sync of 1) to none, and onset sync of 3) to none. That way you might get some screen-tearing artefacts, but the time between them should be microseconds (rather than milliseconds) - making it terribly unlikely that subjects respond at that time.
>
> > But, I don't think this is necessarily the problem. I have a feeling (but correct me if I'm wrong) that time limit of infinite, with duration of 248, might go wrong. How, for example, is E-Prime to know that a late response (after the 248) is for 1) rather than 3)? My suggestion:
> > 1) As you say (with time limit = infinite), but also with jump label (label1) to 4. End
> > 2) makes little sense (search.resp?) Is Search the slide in 1)? If so, then it should be without getattrib (i.e. not reading from list, but from object 1).
> > 3) Slide, as you say, except _without response collection_ (since 1 is doing that).
> > 4) As you say.
> > So, without any code, for once, the stimulus is shown for 250 ms, if participant reacts during that time, they don't see 3. Unless you don't want the stimulus to be presented shorter (perhaps you do EEG?). In which case it might be a bit more difficult:
>
> > 5) Short inline: ExtendedStim.Duration = 250 - Slide1.Duration 'slide1 being whatever you named 1
> > 6) ExtendedStim is a slide that is just a copy (control+drag) of 1). Except it doesn't have keyboard input or collect responses.
>
> > Anyway, the nice thing is that the response is always collected by the same object now, which is at least my preferred way of coding E-Prime.
> > Does that help?
> > Best,
> > Mich
>
> > Michiel Spapé
> > Research Fellow
> > Perception & Action group
> > University of Nottingham
> > School of Psychologywww.cognitology.eu
>
> > -----Original Message-----
> > From: e-prime at googlegroups.com [mailto:e-prime at googlegroups.com] On Behalf Of Tobias
> > Sent: 10 February 2011 18:30
> > To: E-Prime
> > Subject: problem with extended response collection
>
> > Hi,
>
> > i wanna set up the following experiment: A stimulus appears for 250
> > ms. Participants are to respond to that stimulus either during
> > presentation of that stimulus or any time after, when a response
> > screen is shown until the participant reacts. If the participant
> > reacts during stimulus presentation, the response screen should not be
> > displayed.
>
> > I did this as follows:
> > (1) I made a slide that has a duration of 248 ms (should round up to
> > 150 as I use a screen of 100 Hz). I set the time limit to "(infinite)"
> > and the end action to "(none)".
> > (2) After the slide follows an Inline Script with this content:
> > "if c.getattrib("search.resp") = "a" or c.getattrib("search.resp") =
> > "l" then goto Label1"
> > (3) Then follows a slide that serves as a response screen. It has an
> > infinite duration (-1) and "terminate" as an end action.
> > (4) The next element ist the Label1
>
> > This works quite well for most of the trials. If the particpant
> > presses a or l during stimulus ("search") presentation, the inline
> > will make e-prime jump the the label and not call the response screen.
> > If the particpant does not press the button during presentation, the
> > response screen appears until a button is pressed.
>
> > However, sometimes, like about 5% of the trials, participants would
> > have to press twice. That is, even though they pressed a button during
> > stimulus presentation, the response screen appears. My first guess is,
> > that this is because in these rather seldom cases, the participant
> > presses the button in the few milliseconds between stimulus offset and
> > response screen onset. Is that possible? How can I circumvent this
> > problem? Have you had a similar problem?
>
> > Your help is most appreciated!
>
> > Best,
> > Tobias
>
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