Looming pictures

[Michiel Spape]

Hiya all,
Not sure whether this has been said already, but one of the questions was regarding polling the direction of joystick presses. I do know someone else asked this question not too long ago, and also went to e-prime support to ask this. The answer, apparently, was this:

-------------
From: e-prime at googlegroups.com [mailto:e-prime at googlegroups.com] On Behalf Of Nick
Sent: 04 February 2010 22:10
To: E-Prime
Subject: Re: Joystick direction as response & RT

Hi All,

Below is the great solution I received from E-Prime support.  Does
exactly what I need it to, I hope it helps others as well.

If you do not want subjects to press a button after moving the
joystick to the desired position, you can simply access the cursor
position directly instead of checking for a button press. This means
that you should set the Duration of Stimulus to zero so that the
script can be processed immediately; for an example of this method,
please see SAMPLE:Process Responses Template. By constantly checking
the Y position of the cursor, you can determine whether the subject
has responded. Here is an example of the script to use:

Dim nInitY As Integer
Dim nCurrentY As Integer
Dim nDiff As Integer

nInitY = Joystick.CursorY

Do
   nCurrentY = Joystick.CursorY
   nDiff = nInitY - nCurrentY

Loop Until Abs(nDiff) > 50

Stimulus.RTTime = Clock.Read
Stimulus.RT = Stimulus.RTTime - Stimulus.OnsetTime

If nDiff > 0 Then
   Stimulus.RESP = "Up"
Else
   Stimulus.RESP = "Down"
End If
-----------------------



Michiel Spapé
Research Fellow
Perception & Action group
University of Nottingham
School of Psychology


-----Original Message-----
From: e-prime at googlegroups.com [mailto:e-prime at googlegroups.com] On Behalf Of gilis
Sent: 17 June 2010 11:55
To: E-Prime
Subject: Re: Looming pictures

Never tried to do something like this, but it seems that if the
picture size is increasing or decreasing in constant rate for each
pull, then you have to build set of stimuli with the different
possible sizes (a lot of work, there is possibly much easier way if
you have the time and knowledge to program it all into inline that
change the size of given pictures in accordance with its present size
and the direction in which the joystick was pulled) for each picture.

Then, you name each stimulus x as x&"y", with y representing number in
a given direction. Say that if subject pull the joystick six times in
one direction then y=6 and the size of the stimulus is corresponding
to that. Y=0 stand for the stimuli initial size and numbers preceded
by "-", for instance, represent the number of pullings in the opposite
dierction.Then, if the subject pulled the joystick in the positive
numbers direction three times (y=3) and then in the following trial
pulled it in the negative numbers direction you set the Y attrbiute to
Y-1, or to Y+1 in the opposite case. You always have to update your
programe after each trial what is the value of Y.

You do that by setting an attribute called y (c.setattrib "Y", 0+z),
with z dimmed as integer. You have to tell your computer that z=1 in
case of pulling in one direction and -1 in the other direction.

It's only on the surface of the things, and it may be that I'm over
simplfying them, but I think this is a start.

Rgds
Gilis

On Jun 15, 8:05 pm, Craig <cmark... at gmail.com> wrote:
> Hello,
>  I am trying to program a task in which there are looming pictures
> that change depending on the person's response with the joystick.  I
> am currently trying to program an experiment in which pictures are
> presented on the screen, and participants are required to push or pull
> a joystick and squeeze the trigger based on the color of the
> background (e.g., a blue background means push the joystick away).
> When the joystick is pushed, the image size needs to gradually
> decrease (to strengthen the feeling that the picture is pushed
> away). When the joystick is pulled, the image size should increase.
>
> I am using E-prime version 2.0. Professional.  I found a similar
> question on the list, but I didn't see an answer.
>
> I was wondering whether:
> 1) anyone has programmed a looming task where pictures get bigger or
> smaller (I think I need to use the Object Slide, but I am not so sure
> how to do it)
> and
> 2) whether anyone has programmed a task where pressing a joystick in a
> particular direction and squeezing the trigger causes a picture to
> change (i.e.,  how can I collect joystick-movement-data and how I can
> subsequently use this information to present the next picture.).
>   Thanks so much in advance.
>  Craig

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