# Hi all

**URL:** <https://psychtoolbox.discourse.group/t/hi-all/1832>\
**Category:** Uncategorized\
**Created:** [May 23, 2007, 8:46pm UTC](https://psychtoolbox.discourse.group/t/hi-all/1832 "2007-05-23T20:46:39Z")\
**Posts on this page:** 6\
**Page:** 1

<div class="post-metadata">

**Author:** ![Allen\_Ingling](https://avatars.discourse-cdn.com/v4/letter/a/a183cd/32.png) [@Allen\_Ingling](https://psychtoolbox.discourse.group/u/Allen_Ingling)\
**Post date:** [May 23, 2007, 8:46pm UTC](https://psychtoolbox.discourse.group/t/hi-all/1832/1 "2007-05-23T20:46:39Z")

</div>

I'm doing now my M.A thesis work, in which I have to use the psychtoolbox.In my experiment, observers would have to mention in which one of two intervals a Gabor patch was presented (2AFC).I have to use an algorithm that would help me to determine the lowest visible contarst for the Gabor and I also want to restore the results (I'm using two different paradigmsXtwo different conditions).As I'm totaly "green" with Matlab and computing at all, I've no idea where to start from -can any body help me?

Best

Gilad Sabo

* * *
[Pinpoint customers](http://us.rd.yahoo.com/evt=48250/*http://searchmarketing.yahoo.com/arp/sponsoredsearch_v9.php?o=US2226&cmp=Yahoo&ctv=AprNI&s=Y&s2=EM&b=50)who are looking for what you sell.

---

<div class="post-metadata">

**Author:** ![Allen\_Ingling](https://avatars.discourse-cdn.com/v4/letter/a/a183cd/32.png) [@Allen\_Ingling](https://psychtoolbox.discourse.group/u/Allen_Ingling)\
**Post date:** [May 29, 2007, 7:58pm UTC](https://psychtoolbox.discourse.group/t/hi-all/1832/2 "2007-05-29T19:58:12Z")

</div>

Check out this tutorial:  
  
[psychtoolbox.org/PTB-2/download/](http://psychtoolbox.org/PTB-2/download/) **Fine**** Tutorial**/revision\_2/MatClassAll.pdf  
  
by Ione Fine.  
  
cheers,  
maria  
  

On 5/29/07, **florian.stendel** \<[vincentdhs@...](mailto:vincentdhs@...)\> wrote:

> > Hi Gilad,  
> >   
> > this sounds like a huge duty too me, since you never programmed, right?  
> >   
> > Imho,as long as you don't have basic knowledge in programming nobody would(better   
> > say: would have the time to) help you.  
> >   
> > Someone maybe could post you a whole source code (if i would knew the algorithm and   
> > parameters of your experiment) but this wouldn' help you.  
> >   
> > Anyway....if you have any questions, just drop me a mail....  
> >   
> > regards  
> >   
> > Florian   
> >   
> > --- In [psychtoolbox@yahoogroups.com](mailto:psychtoolbox%40yahoogroups.com), gili sabo \<gilisabo@...\> wrote:  
> > \>  
> > \> I'm doing now my M.A thesis work, in which I have to use the psychtoolbox.In my   
> > experiment, observers would have to mention in which one of two intervals a Gabor patch   
> > was presented (2AFC).I have to use an algorithm that would help me to determine the   
> > lowest visible contarst for the Gabor and I also want to restore the results (I'm using two   
> > different paradigmsXtwo different conditions).As I'm totaly "green" with Matlab and   
> > computing at all, I've no idea where to start from -can any body help me?  
> > \> Best  
> > \> Gilad Sabo  
> > \>   
> > \>   
> > \> ---------------------------------  
> > \> Pinpoint customers who are looking for what you sell.  
> > \>

  
  
  
--   
Maria Mckinley  
Scientific Programmer  
Shadlen Lab  
Physiology and Biophysics  
Box 357290  
University of Washington  
(206) 616-3923  
[parody@...](mailto:parody@...)

---

<div class="post-metadata">

**Author:** ![tudorcb](https://avatars.discourse-cdn.com/v4/letter/t/91b2a8/32.png) [@tudorcb](https://psychtoolbox.discourse.group/u/tudorcb)\
**Post date:** [May 31, 2007, 3:54am UTC](https://psychtoolbox.discourse.group/t/hi-all/1832/3 "2007-05-31T03:54:48Z")

</div>

Hi Mario,  
  
here is Tudor, the guy with the ugly bullseye code.   
That was destined to produce concentric circles to be  
shown rom quicktime, so it is done with. But i am on  
to my next project. I will be for the most part,  
presenting visual stimuli to a retina through a  
microscope objective. I am currently setting up the  
system. So i am looking at this Dell computer screen  
(with a 85Hz refresh rate), and whenever i use one of  
the simple things like draw dot or similar stuff, i  
see some black and white vertical lines running  
through my entire field, underlying whatever stimulus  
i am presenting. I tried this also by presenting the  
stimuli from the screen of my PowerBook G4, and i get  
a simmilar thing. i am wondering whether it is  
because i am missing something fundamental, or whetehr  
this is what aeveyone sees when they look at a  
computer screen with a magnifying lens (which is  
basically what i am doing here).  
  
  
Tudor  
  
  
--- Mario Kleiner \<[mario.kleiner@...](mailto:mario.kleiner@...)\>  
wrote:  
  

> \> This one...  
> \>   
> \> \<[http://www.rcbi.rochester.edu/~ks/ptb.htm](http://www.rcbi.rochester.edu/~ks/ptb.htm)\>  
> \>   
> \> is a different tutorial by Keith Schneider from  
> \> Rochester. Up to now  
> \> the best one i've found related to Matlab +  
> \> Psychtoolbox-3.  
> \> The tutorial mentioned by Maria is nicely made, but  
> \> refers to  
> \> the old PTB-2, so many of the practices demonstrated  
> \> there  
> \> don't really apply to PTB-3 any more.  
> \>   
> \> Other than that, looking at our PsychDemos is always  
> \> a good idea  
> \> to get ideas on how to solve some tasks and how to  
> \> do stuff in  
> \> an efficient way. You'll have to look at many of  
> \> them, given  
> \> that each of them demonstrates different concepts  
> \>   
> \> -mario  
> \>   
> \> --- In [psychtoolbox@yahoogroups.com](mailto:psychtoolbox@yahoogroups.com), "gilisabo"  
> \> \<gilisabo@...\> wrote:  
> \> \>  
> \> \> Hi Maria   
> \> \> 10x for your advises, can you send me the link  
> \> again (this one isn't   
> \> \> working)? any ways, I solve some of my major  
> \> problems (I find it easy   
> \> \> to program -using good guiding)-but I still have  
> \> some questions left'   
> \> \> like: how can I define the spatial frequency of  
> \> any given Gabor?  
> \> \> Best  
> \> \> Gilad  
> \> \>  
> \>   
> \>

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_Looking for a deal? Find great prices on flights and hotels with Yahoo! FareChase.  
[http://farechase.yahoo.com/](http://farechase.yahoo.com/)

---

<div class="post-metadata">

**Author:** ![tudorcb](https://avatars.discourse-cdn.com/v4/letter/t/91b2a8/32.png) [@tudorcb](https://psychtoolbox.discourse.group/u/tudorcb)\
**Post date:** [June 1, 2007, 12:19am UTC](https://psychtoolbox.discourse.group/t/hi-all/1832/4 "2007-06-01T00:19:56Z")

</div>

Danke Mario,  
  
ich hatte schon begonnen zu glauben ich "sehe" Sachen  
die es nicht gibt.  
  
In any case, i do have a few old trinitron tubes lying  
around the lab - nobody wants them, everyone is into  
flatscreens. So i will have to haul them downstairs,  
put them in front of my setup and see what happens.  
  
That's almost all, until i start data analysis.  
Cheers, and thanks a bunch.  
  
Tudor  
--- Mario Kleiner \<[mario.kleiner@...](mailto:mario.kleiner@...)\>  
wrote:  
  

> \> Not an expert, but could it be this what you're  
> \> seeing?  
> \>   
> \>

\<[http://www.epinions.com/cmd-review-68E6-1273DC21-3839F1FF-bd4](http://www.epinions.com/cmd-review-68E6-1273DC21-3839F1FF-bd4)\>  

> \>   
> \> At high magnification levels you will see the  
> \> separating wire arrangemnt,  
> \> or mask pattern on a non-Trinitron monitor, or the  
> \> transistor matrix of  
> \> a lcd panel. Maybe you'll need some kind of diffusor  
> \> in front of your screen  
> \> to blur the image out?  
> \>   
> \> "I know everything because i can google, use  
> \> Wikipedia and  
> \> make things up if i don't know the real answer,  
> \> rather than  
> \> confess i don't know the answer."  
> \> -mario  
> \>   
> \>   
> \> --- In [psychtoolbox@yahoogroups.com](mailto:psychtoolbox@yahoogroups.com), tudor badea  
> \> \<tudorcb@...\> wrote:  
> \> \>  
> \> \> Hi Mario,  
> \> \>   
> \> \> here is Tudor, the guy with the ugly bullseye  
> \> code.   
> \> \> That was destined to produce concentric circles to  
> \> be  
> \> \> shown rom quicktime, so it is done with. But i am  
> \> on  
> \> \> to my next project. I will be for the most part,  
> \> \> presenting visual stimuli to a retina through a  
> \> \> microscope objective. I am currently setting up  
> \> the  
> \> \> system. So i am looking at this Dell computer  
> \> screen  
> \> \> (with a 85Hz refresh rate), and whenever i use one  
> \> of  
> \> \> the simple things like draw dot or similar stuff,  
> \> i  
> \> \> see some black and white vertical lines running  
> \> \> through my entire field, underlying whatever  
> \> stimulus  
> \> \> i am presenting. I tried this also by presenting  
> \> the  
> \> \> stimuli from the screen of my PowerBook G4, and i  
> \> get  
> \> \> a simmilar thing. i am wondering whether it is  
> \> \> because i am missing something fundamental, or  
> \> whetehr  
> \> \> this is what aeveyone sees when they look at a  
> \> \> computer screen with a magnifying lens (which is  
> \> \> basically what i am doing here).  
> \> \>   
> \> \>   
> \> \> Tudor  
> \> \>   
> \> \>   
> \> \> --- Mario Kleiner \<mario.kleiner@...\>  
> \> \> wrote:  
> \> \>   
> \> \> \> This one...  
> \> \> \>   
> \> \> \> \<[http://www.rcbi.rochester.edu/~ks/ptb.htm](http://www.rcbi.rochester.edu/~ks/ptb.htm)\>  
> \> \> \>   
> \> \> \> is a different tutorial by Keith Schneider from  
> \> \> \> Rochester. Up to now  
> \> \> \> the best one i've found related to Matlab +  
> \> \> \> Psychtoolbox-3.  
> \> \> \> The tutorial mentioned by Maria is nicely made,  
> \> but  
> \> \> \> refers to  
> \> \> \> the old PTB-2, so many of the practices  
> \> demonstrated  
> \> \> \> there  
> \> \> \> don't really apply to PTB-3 any more.  
> \> \> \>   
> \> \> \> Other than that, looking at our PsychDemos is  
> \> always  
> \> \> \> a good idea  
> \> \> \> to get ideas on how to solve some tasks and how  
> \> to  
> \> \> \> do stuff in  
> \> \> \> an efficient way. You'll have to look at many of  
> \> \> \> them, given  
> \> \> \> that each of them demonstrates different  
> \> concepts  
> \> \> \>   
> \> \> \> -mario  
> \> \> \>   
> \> \> \> --- In [psychtoolbox@yahoogroups.com](mailto:psychtoolbox@yahoogroups.com), "gilisabo"  
> \> \> \> \<gilisabo@\> wrote:  
> \> \> \> \>  
> \> \> \> \> Hi Maria   
> \> \> \> \> 10x for your advises, can you send me the link  
> \> \> \> again (this one isn't   
> \> \> \> \> working)? any ways, I solve some of my major  
> \> \> \> problems (I find it easy   
> \> \> \> \> to program -using good guiding)-but I still  
> \> have  
> \> \> \> some questions left'   
> \> \> \> \> like: how can I define the spatial frequency  
> \> of  
> \> \> \> any given Gabor?  
> \> \> \> \> Best  
> \> \> \> \> Gilad  
> \> \> \> \>  
> \> \> \>   
> \> \> \>   
> \> \>   
> \> \>   
> \> \>   
> \> \>   
> \> \>   
> \>

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_Loo  

> \> king for a deal? Find great prices on flights and  
> \> hotels with Yahoo! FareChase.  
> \> \> [http://farechase.yahoo.com/](http://farechase.yahoo.com/)  
> \> \>  
> \>   
> \>

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_  
Be a better Globetrotter. Get better travel answers from someone who knows. Yahoo! Answers - Check it out.  
[http://answers.yahoo.com/dir/?link=list&sid=396545469](http://answers.yahoo.com/dir/?link=list&sid=396545469)

---

<div class="post-metadata">

**Author:** ![denispelli](https://avatars.discourse-cdn.com/v4/letter/d/cdc98d/32.png) [@denispelli](https://psychtoolbox.discourse.group/u/denispelli)\
**Post date:** [June 1, 2007, 2:18am UTC](https://psychtoolbox.discourse.group/t/hi-all/1832/5 "2007-06-01T02:18:55Z")

</div>

Denis Pelli

Professor of Psychology and Neural Science

[http://psych.nyu.edu/pelli/](http://psych.nyu.edu/pelli/)
  
 
  

On May 31, 2007, at 8:19 PM, tudor badea wrote:
  

> > Danke Mario,  
> >   
> > ich hatte schon begonnen zu glauben ich "sehe" Sachen  
> > die es nicht gibt.  
> >   
> > In any case, i do have a few old trinitron tubes lying  
> > around the lab - nobody wants them, everyone is into  
> > flatscreens. So i will have to haul them downstairs,  
> > put them in front of my setup and see what happens.  
> >   
> > That's almost all, until i start data analysis.  
> > Cheers, and thanks a bunch.  
> >   
> > Tudor  
> > --- Mario Kleiner \<[mario.kleiner@tuebingen.mpg.de](mailto:mario.kleiner%40tuebingen.mpg.de)\>  
> > wrote:  
> >   
> > \> Not an expert, but could it be this what you're  
> > \> seeing?  
> > \>   
> > \>  
> > \<[http://www.epinions.com/cmd-review-68E6-1273DC21-3839F1FF-bd4](http://www.epinions.com/cmd-review-68E6-1273DC21-3839F1FF-bd4)\>  
> > \>   
> > \> At high magnification levels you will see the  
> > \> separating wire arrangemnt,  
> > \> or mask pattern on a non-Trinitron monitor, or the  
> > \> transistor matrix of  
> > \> a lcd panel. Maybe you'll need some kind of diffusor  
> > \> in front of your screen  
> > \> to blur the image out?  
> > \>   
> > \> "I know everything because i can google, use  
> > \> Wikipedia and  
> > \> make things up if i don't know the real answer,  
> > \> rather than  
> > \> confess i don't know the answer."  
> > \> -mario  
> > \>   
> > \>   
> > \> --- In [psychtoolbox@yahoogroups.com](mailto:psychtoolbox%40yahoogroups.com), tudor badea  
> > \> \<tudorcb@...\> wrote:  
> > \> \>  
> > \> \> Hi Mario,  
> > \> \>   
> > \> \> here is Tudor, the guy with the ugly bullseye  
> > \> code.   
> > \> \> That was destined to produce concentric circles to  
> > \> be  
> > \> \> shown rom quicktime, so it is done with. But i am  
> > \> on  
> > \> \> to my next project. I will be for the most part,  
> > \> \> presenting visual stimuli to a retina through a  
> > \> \> microscope objective. I am currently setting up  
> > \> the  
> > \> \> system. So i am looking at this Dell computer  
> > \> screen  
> > \> \> (with a 85Hz refresh rate), and whenever i use one  
> > \> of  
> > \> \> the simple things like draw dot or similar stuff,  
> > \> i  
> > \> \> see some black and white vertical lines running  
> > \> \> through my entire field, underlying whatever  
> > \> stimulus  
> > \> \> i am presenting. I tried this also by presenting  
> > \> the  
> > \> \> stimuli from the screen of my PowerBook G4, and i  
> > \> get  
> > \> \> a simmilar thing. i am wondering whether it is  
> > \> \> because i am missing something fundamental, or  
> > \> whetehr  
> > \> \> this is what aeveyone sees when they look at a  
> > \> \> computer screen with a magnifying lens (which is  
> > \> \> basically what i am doing here).  
> > \> \>   
> > \> \>   
> > \> \> Tudor  
> > \> \>   
> > \> \>   
> > \> \> --- Mario Kleiner \<mario.kleiner@...\>  
> > \> \> wrote:  
> > \> \>   
> > \> \> \> This one...  
> > \> \> \>   
> > \> \> \> \<[http://www.rcbi.](http://www.rcbi.rochester.edu/~ks/ptb.htm)rochester.edu/~ks/ptb.htm\>  
> > \> \> \>   
> > \> \> \> is a different tutorial by Keith Schneider from  
> > \> \> \> Rochester. Up to now  
> > \> \> \> the best one i've found related to Matlab +  
> > \> \> \> Psychtoolbox-3.  
> > \> \> \> The tutorial mentioned by Maria is nicely made,  
> > \> but  
> > \> \> \> refers to  
> > \> \> \> the old PTB-2, so many of the practices  
> > \> demonstrated  
> > \> \> \> there  
> > \> \> \> don't really apply to PTB-3 any more.  
> > \> \> \>   
> > \> \> \> Other than that, looking at our PsychDemos is  
> > \> always  
> > \> \> \> a good idea  
> > \> \> \> to get ideas on how to solve some tasks and how  
> > \> to  
> > \> \> \> do stuff in  
> > \> \> \> an efficient way. You'll have to look at many of  
> > \> \> \> them, given  
> > \> \> \> that each of them demonstrates different  
> > \> concepts  
> > \> \> \>   
> > \> \> \> -mario  
> > \> \> \>   
> > \> \> \> --- In [psychtoolbox@](mailto:psychtoolbox%40yahoogroups.com)yahoogroups.com, "gilisabo"  
> > \> \> \> \<gilisabo@\> wrote:  
> > \> \> \> \>  
> > \> \> \> \> Hi Maria   
> > \> \> \> \> 10x for your advises, can you send me the link  
> > \> \> \> again (this one isn't   
> > \> \> \> \> working)? any ways, I solve some of my major  
> > \> \> \> problems (I find it easy   
> > \> \> \> \> to program -using good guiding)-but I still  
> > \> have  
> > \> \> \> some questions left'   
> > \> \> \> \> like: how can I define the spatial frequency  
> > \> of  
> > \> \> \> any given Gabor?  
> > \> \> \> \> Best  
> > \> \> \> \> Gilad  
> > \> \> \> \>  
> > \> \> \>   
> > \> \> \>   
> > \> \>   
> > \> \>   
> > \> \>   
> > \> \>   
> > \> \>   
> > \>  
> > \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_Loo  
> > \> king for a deal? Find great prices on flights and  
> > \> hotels with Yahoo! FareChase.  
> > \> \> [http://farechase.](http://farechase.yahoo.com/)yahoo.com/  
> > \> \>  
> > \>   
> > \>   
> >   
> > \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_  
> > Be a better Globetrotter. Get better travel answers from someone who knows. Yahoo! Answers - Check it out.  
> > [http://answers.](http://answers.yahoo.com/dir/?link=list&sid=396545469)yahoo.com/dir/?link=list&sid=396545469

---

<div class="post-metadata">

**Author:** ![tudorcb](https://avatars.discourse-cdn.com/v4/letter/t/91b2a8/32.png) [@tudorcb](https://psychtoolbox.discourse.group/u/tudorcb)\
**Post date:** [June 6, 2007, 11:07pm UTC](https://psychtoolbox.discourse.group/t/hi-all/1832/6 "2007-06-06T23:07:33Z")

</div>

Hi Mario  
  
i have checked the trintitron, and unfotunatelly , the lines are still there.  
  
regarding the stripes that are visible on the screen, i have tested a sony trinitron multiscan   
420GS. The vertical stripes are still there, in addition there are also horizontal ones (that   
may have been there in the others as well, just missed since out of focus). I used a   
random noise stimulus interrupted with a kbwait to check the size of these things, and i   
can tell you that   
  
at 640 x 480 pixel screen setting, with 85Hz refresh rate, each pixel is cut through by one   
vertical line, yielding 2 rectangles.  
  
at 1600 x 1200 pixel screen setting, with 60Hz refresh rate, each pixel is within the limits   
of one line, so i guess one can use this screen setting. Now your visual stimulus is   
actually looking like a backgammon board, with each pixel framed by lines.   
  
An imperfect way is to alter the distance of the objective that collects the stimulus such   
that the grid is out of focus, but the pixels are still fairly sharp.   
  
If you make scaled "pixels", so squares of 4x4 pixels, you can also observe horizontal   
lines, that occur with a frequency of half the vertical ones.   
  
Pehaps another way is to set the screen way back and create artificially larger pixels. At   
that point you can probably get ridd of the lines by moving the focus a little.   
  
I am still kind of puzzled as to why other people have not seen this before.   
  
Tudor  
  
  
  

> \> \>  
> \> \> In any case, i do have a few old trinitron tubes lying  
> \> \> around the lab - nobody wants them, everyone is into  
> \> \> flatscreens. So i will have to haul them downstairs,  
> \> \> put them in front of my setup and see what happens.  
> \> \>  
> \> \> That's almost all, until i start data analysis.  
> \> \> Cheers, and thanks a bunch.  
> \> \>  
> \> \> Tudor  
> \> \> --- Mario Kleiner \<mario.kleiner@...\>  
> \> \> wrote:  
> \> \>  
> \> \> \> Not an expert, but could it be this what you're  
> \> \> \> seeing?  
> \> \> \>  
> \> \> \>  
> \> \> \<[http://www.epinions.com/cmd-review-68E6-1273DC21-3839F1FF-bd4](http://www.epinions.com/cmd-review-68E6-1273DC21-3839F1FF-bd4)\>  
> \> \> \>  
> \> \> \> At high magnification levels you will see the  
> \> \> \> separating wire arrangemnt,  
> \> \> \> or mask pattern on a non-Trinitron monitor, or the  
> \> \> \> transistor matrix of  
> \> \> \> a lcd panel. Maybe you'll need some kind of diffusor  
> \> \> \> in front of your screen  
> \> \> \> to blur the image out?  
> \> \> \>  
> \> \> \> "I know everything because i can google, use  
> \> \> \> Wikipedia and  
> \> \> \> make things up if i don't know the real answer,  
> \> \> \> rather than  
> \> \> \> confess i don't know the answer."  
> \> \> \> -mario  
> \> \> \>  
> \> \> \>  
> \> \> \> --- In [psychtoolbox@yahoogroups.com](mailto:psychtoolbox@yahoogroups.com), tudor badea  
> \> \> \> \<tudorcb@\> wrote:  
> \> \> \> \>  
> \> \> \> \> Hi Mario,  
> \> \> \> \>  
> \> \> \> \> here is Tudor, the guy with the ugly bullseye  
> \> \> \> code.  
> \> \> \> \> That was destined to produce concentric circles to  
> \> \> \> be  
> \> \> \> \> shown rom quicktime, so it is done with. But i am  
> \> \> \> on  
> \> \> \> \> to my next project. I will be for the most part,  
> \> \> \> \> presenting visual stimuli to a retina through a  
> \> \> \> \> microscope objective. I am currently setting up  
> \> \> \> the  
> \> \> \> \> system. So i am looking at this Dell computer  
> \> \> \> screen  
> \> \> \> \> (with a 85Hz refresh rate), and whenever i use one  
> \> \> \> of  
> \> \> \> \> the simple things like draw dot or similar stuff,  
> \> \> \> i  
> \> \> \> \> see some black and white vertical lines running  
> \> \> \> \> through my entire field, underlying whatever  
> \> \> \> stimulus  
> \> \> \> \> i am presenting. I tried this also by presenting  
> \> \> \> the  
> \> \> \> \> stimuli from the screen of my PowerBook G4, and i  
> \> \> \> get  
> \> \> \> \> a simmilar thing. i am wondering whether it is  
> \> \> \> \> because i am missing something fundamental, or  
> \> \> \> whetehr  
> \> \> \> \> this is what aeveyone sees when they look at a  
> \> \> \> \> computer screen with a magnifying lens (which is  
> \> \> \> \> basically what i am doing here).  
> \> \> \> \>  
> \> \> \> \>  
> \> \> \> \> Tudor  
> \> \> \> \>  
> \> \> \> \>  
> \> \> \> \> --- Mario Kleiner \<mario.kleiner@\>  
> \> \> \> \> wrote:  
> \> \> \> \>  
> \> \> \> \> \> This one...  
> \> \> \> \> \>  
> \> \> \> \> \> \<[http://www.rcbi.rochester.edu/~ks/ptb.htm](http://www.rcbi.rochester.edu/~ks/ptb.htm)\>  
> \> \> \> \> \>  
> \> \> \> \> \> is a different tutorial by Keith Schneider from  
> \> \> \> \> \> Rochester. Up to now  
> \> \> \> \> \> the best one i've found related to Matlab +  
> \> \> \> \> \> Psychtoolbox-3.  
> \> \> \> \> \> The tutorial mentioned by Maria is nicely made,  
> \> \> \> but  
> \> \> \> \> \> refers to  
> \> \> \> \> \> the old PTB-2, so many of the practices  
> \> \> \> demonstrated  
> \> \> \> \> \> there  
> \> \> \> \> \> don't really apply to PTB-3 any more.  
> \> \> \> \> \>  
> \> \> \> \> \> Other than that, looking at our PsychDemos is  
> \> \> \> always  
> \> \> \> \> \> a good idea  
> \> \> \> \> \> to get ideas on how to solve some tasks and how  
> \> \> \> to  
> \> \> \> \> \> do stuff in  
> \> \> \> \> \> an efficient way. You'll have to look at many of  
> \> \> \> \> \> them, given  
> \> \> \> \> \> that each of them demonstrates different  
> \> \> \> concepts  
> \> \> \> \> \>  
> \> \> \> \> \> -mario  
> \> \> \> \> \>  
> \> \> \> \> \> --- In [psychtoolbox@yahoogroups.com](mailto:psychtoolbox@yahoogroups.com), "gilisabo"  
> \> \> \> \> \> \<gilisabo@\> wrote:  
> \> \> \> \> \> \>  
> \> \> \> \> \> \> Hi Maria  
> \> \> \> \> \> \> 10x for your advises, can you send me the link  
> \> \> \> \> \> again (this one isn't  
> \> \> \> \> \> \> working)? any ways, I solve some of my major  
> \> \> \> \> \> problems (I find it easy  
> \> \> \> \> \> \> to program -using good guiding)-but I still  
> \> \> \> have  
> \> \> \> \> \> some questions left'  
> \> \> \> \> \> \> like: how can I define the spatial frequency  
> \> \> \> of  
> \> \> \> \> \> any given Gabor?  
> \> \> \> \> \> \> Best  
> \> \> \> \> \> \> Gilad  
> \> \> \> \> \> \>  
> \> \> \> \> \>  
> \> \> \> \> \>  
> \> \> \> \>  
> \> \> \> \>  
> \> \> \> \>  
> \> \> \> \>  
> \> \> \> \>  
> \> \> \>  
> \> \> \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_Loo  
> \> \> \> king for a deal? Find great prices on flights and  
> \> \> \> hotels with Yahoo! FareChase.  
> \> \> \> \> [http://farechase.yahoo.com/](http://farechase.yahoo.com/)  
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> \> \> \>  
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> \> \> Be a better Globetrotter. Get better travel answers from someone   
> \> \> who knows. Yahoo! Answers - Check it out.  
> \> \> [http://answers.yahoo.com/dir/?link=list&sid=396545469](http://answers.yahoo.com/dir/?link=list&sid=396545469)  
> \> \>  
> \> \>  
> \>