Re: stimulus size in degrees of visual angle

[David McFarlane]

Maggie,

E-Prime displays work in units of pixels, or
%. You will have to convert that to visual
angle. To do that you will have to know the
physical dimensions of your screen, and the
distance from the observer to the screen. From
there it is just a little bit of math, which you
can find in the Wikipedia article on "Visual
angle". You should be able to take it from there.

(Aside to PsychoPy users: Yes, PsychoPy, unlike
E-Prime, will work directly in units of visual
angle, after you tell it the measurements mentioned above.)

-----
David McFarlane
E-Prime training
online: http://psychology.msu.edu/Workshops_Courses/eprime.aspx
Twitter: @EPrimeMaster (https://twitter.com/EPrimeMaster )

/----
Stock reminder: 1) I do not work for PST. 2)
PST's trained staff take any and all questions at
https://support.pstnet.com , and they strive to
respond to all requests in 24-48 hours, so make
full use of it. 3) In addition, PST offers
several instructional videos on their YouTube
channel (http://www.youtube.com/user/PSTNET
). 4) If you do get an answer from PST staff,
please extend the courtesy of posting their reply
back here for the sake of others.
\----


At 10/17/2013 09:26 AM Thursday, Maggie wrote:
>Hello,
>
>I'm just starting to learn how to use eprime and
>I've run into some trouble with the stimulus
>size. I need to place a geometric shape (i.e.
>triangle or square) above the fixation point,
>and it needs to be 3.8° x 3.8° in size. How to I
>convert this into pixels exactly? I'm assuming
>the size (height and width) in properties are in pixels too, right?
>
>Many thanks,
>Maggie

[jacant...@gmail.com]

Hi
If u want to use eprime then, AFAIK, you will need to do some basic trigonometry to convert angles into mm and then into pixels.
You might like to look at PsychoPy instead though. It has the concept of monitor dimensions and viewing angles builtin so this may be a lot simpler. Its free too :) and works across all platforms too.
John

On 17 Oct 2013 14:26, "Maggie" <meng...@gmail.com> wrote:

Hello,

 

I'm just starting to learn how to use eprime and I've run into some trouble with the stimulus size. I need to place a geometric shape (i.e. triangle or square) above the fixation point, and it needs to be 3.8° x 3.8° in size. How to I convert this into pixels exactly? I'm assuming the size (height and width) in properties are in pixels too, right?

 

Many thanks,

Maggie

 

 

 

--
You received this message because you are subscribed to the Google Groups "E-Prime" group.
To unsubscribe from this group and stop receiving emails from it, send an email to e-prime+u...@googlegroups.com.
To post to this group, send email to e-p...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/e-prime/431e3b8b-57b3-4eb1-9904-9d60c3bddce8%40googlegroups.com.
For more options, visit https://groups.google.com/groups/opt_out.