Howdy, Stranger!

It looks like you're new here. If you want to get involved, click one of these buttons!

Supported by

[open] Need to define the location of the stimulus on the screen to the degree.. Please help!

edited October 2013 in OpenSesame

Hi.. I'm conducting an experiment where I need to present the stimuli 2.5-3° left or right to the central fixation. I'm gonna need to use images and words. Please tell me its possible using Open Sesame!!


  • edited October 2013


    Recalculating visual angles (I assume you mean visual angle, not a rotation) to pixel distances is something you can do yourself, either using OpenSesame, or a calculator.

    You can find the formula on how to calculate a distance on a flat screen based on a visual angle on Wikipedia.

    The next thing you would need to do is calculate the amount of pixels per centimeters your screen contains, which is rather easy as well: measure the screen width, then divide the (horizontal) display resolution by your measurement.

    You'll find an example below. Just fill in your own values when you want to do this yourself.

    Good luck!




    visual angle (V): 3 degrees


    distance screen-participant (D): 57 cm

    screen width: 33.8 cm

    display resolution: 1280x1024 (pixels)


    distance on monitor (S) = tangent of the visual angle multiplied by the distance screen-participant

    S = tan(V) * D = tan(3°) / 57 cm = 2.98 cm

    amount of pixels per centimeter = (horizontal) display resolution / display width

    pix/cm = 1280 pixels / 33.8 cm = 37.9 pixels per cm

    distance on monitor in pixels = distance on monitor in centimeters multiplied with amount of pixels per centimeter

    S * px/cm = 2.98 cm * 37.9 pixels per centimeter = 113 pixels

  • edited October 2013

    Thank You Edwin!! That was a big help. :)
    However, I still don't know WHERE to input these values in Open Sesame? Do I find the desired width and height of the stimulus based on these values and then input them as the (x,y) coordinates in the 'Grid' option given?

    Please forgive the number of my questions. I'm quite new to this.

  • edited October 2013

    Glad I could help!

    If you're new to this, the tutorial might be really useful. These will learn you how to create stimuli. Just keep in mind that all of the numbers that indicate stimulus position and size in OpenSesame are in pixels. Use the method I posted earlier to recalculate all of your sizes in visual angle to pixels. Then use the values you've calculated in OpenSesame.

    General tutorial:

    Video tutorials:

    Good luck!

  • edited February 2019

    Hi @Edwin,

    Sorry if this question comes across a bit daft, but here we go.

    I've been using your formula above to recreate stimuli size and position on a new monitor with a high resolution.

    The resolution is as follows: 5120*2880 (which I've set to match in the experiment).

    The width of the display screen is 59.4cm.

    If I'm not mistaken the following calculation will give me pix per cm:

    5120/59.4 = 86.19529 pix per cm

    Therefore if I want to determine the size of the radius in pix of circle with a cm radius of 1.725 I'd do the following:

    86.19529*1.725 = 148.6869 pix

    I do something similar for the distance from fixation to the centre of the circle:

    86.19529*12.93103cm = 1114.594 pix

    However when I measure the size/distance in real terms via measuring tape they are way off when displayed via OpenSesame.

    I'm guessing something is amiss in my calculation as when I divide the above values by 2 and re-input the divided values into OpenSesame the size/distance is correct.

    I'm displaying on a 27" Mac.

    Any thoughts?



  • edited February 2019

    Hi @booradley,

    That might not actually be a very daft question at all! Because the resolution is quite high, I imagine there might be a layer of software in between OpenSesame and the actual display. What resolution does OpenSesame think the display is?

    EDIT: Oh, I just realised you actually mentioned this in your question! Is there anything in your output that suggests the window is resized to a value you didn't set it to? PsychoPy will do this, but it will also print out a message to the Debug Window telling you that it did.


  • Hi @Edwin,

    I'll check that when I'm in the lab next and get back to you. Good to hear that I may not be totally bonkers after all.



Sign In or Register to comment.

agen judi bola , sportbook, casino, togel, number game, singapore, tangkas, basket, slot, poker, dominoqq, agen bola. Semua permainan bisa dimainkan hanya dengan 1 ID. minimal deposit 50.000 ,- bonus cashback hingga 10% , diskon togel hingga 66% bisa bermain di android dan IOS kapanpun dan dimana pun. poker , bandarq , aduq, domino qq , dominobet. Semua permainan bisa dimainkan hanya dengan 1 ID. minimal deposit 10.000 ,- bonus turnover 0.5% dan bonus referral 20%. Bonus - bonus yang dihadirkan bisa terbilang cukup tinggi dan memuaskan, anda hanya perlu memasang pada situs yang memberikan bursa pasaran terbaik yaitu Bola168. Situs penyedia segala jenis permainan poker online kini semakin banyak ditemukan di Internet, salah satunya TahunQQ merupakan situs Agen Judi Domino66 Dan BandarQ Terpercaya yang mampu memberikan banyak provit bagi bettornya. Permainan Yang Di Sediakan Dewi365 Juga sangat banyak Dan menarik dan Peluang untuk memenangkan Taruhan Judi online ini juga sangat mudah . Mainkan Segera Taruhan Sportbook anda bersama Agen Judi Bola Bersama Dewi365 Kemenangan Anda Berapa pun akan Terbayarkan. Tersedia 9 macam permainan seru yang bisa kamu mainkan hanya di dalam 1 ID saja. Permainan seru yang tersedia seperti Poker, Domino QQ Dan juga BandarQ Online. Semuanya tersedia lengkap hanya di ABGQQ. Situs ABGQQ sangat mudah dimenangkan, kamu juga akan mendapatkan mega bonus dan setiap pemain berhak mendapatkan cashback mingguan. ABGQQ juga telah diakui sebagai Bandar Domino Online yang menjamin sistem FAIR PLAY disetiap permainan yang bisa dimainkan dengan deposit minimal hanya Rp.25.000. DEWI365 adalah Bandar Judi Bola Terpercaya & resmi dan terpercaya di indonesia. Situs judi bola ini menyediakan fasilitas bagi anda untuk dapat bermain memainkan permainan judi bola. Didalam situs ini memiliki berbagai permainan taruhan bola terlengkap seperti Sbobet, yang membuat DEWI365 menjadi situs judi bola terbaik dan terpercaya di Indonesia. Tentunya sebagai situs yang bertugas sebagai Bandar Poker Online pastinya akan berusaha untuk menjaga semua informasi dan keamanan yang terdapat di POKERQQ13. Kotakqq adalah situs Judi Poker Online Terpercayayang menyediakan 9 jenis permainan sakong online, dominoqq, domino99, bandarq, bandar ceme, aduq, poker online, bandar poker, balak66, perang baccarat, dan capsa susun. Dengan minimal deposit withdraw 15.000 Anda sudah bisa memainkan semua permaina pkv games di situs kami. Jackpot besar,Win rate tinggi, Fair play, PKV Games