Download, Installation, and Update

Make sure to familiarize yourself with the System requirements, so your system is set up with suitable hardware and additional required software before installing Psychtoolbox itself.

In order to install and use the Psychtoolbox, you must already have Matlab or Octave installed on your computer, unless you install for Octave on Linux via the NeuroDebian repositories. If you already have Matlab or Octave installed, start it up and read on. On Windows you must have installed GStreamer 1.22.5 MSVC edition or later versions.



First, you should make sure you don’t already have Psychtoolbox-3. Type the following in the Matlab command window:

>> PsychtoolboxVersion

The first number in the output is the version number. If it is 3.0.8 or greater, then you have Psychtoolbox-3. Pick one:

  1. If you have an older version of Psychtoolbox than 3.0.8, remove it by following the instructions in the next section, Removing Old Versions
  2. If you don’t have Psychtoolbox-3 at all, read the Installation Instructions below.
  3. If you do have it, skip down to the Staying Up-to-Date section below.

Removing Old Versions of Psychtoolbox

If you have an old version of Psychtoolbox installed, the installer will prompt you if it should automatically delete those version from your file system and do so if you agree. If you want to delete the folder manually, apply the following procedure.

To find the Psychtoolbox installation directory, type the following in the Matlab command window:

>> PsychtoolboxRoot

Find that folder and drag it to the Trash or Recycling Bin. Then type pathtool in the Matlab command window. This will bring up a dialog box with a list of folders that Matlab searches to find commands. Select all the folders that have “Psychtoolbox” in the name and click the “Remove” button, followed by the “Save” button to save the changes.

Installation Instructions

These are simple instructions to get you up and running with the Psychophysics Toolbox on a computer. It is assumed that you already have Matlab or Octave installed on your computer, or you are installing for Octave on Linux via the NeuroDebian repositories. See the System Requirements.



Psychtoolbox for Linux has been packaged by the NeuroDebian team and is available in the following repositories:

Usually reasonably up to date, tracks most recent official PTB beta releases - recommended for most “bread and butter” use cases:

NeuroDebian provides installation instructions on its website when you click on the links for Octave or Matlab above.

If you installed Matlab before installing Psychtoolbox for Matlab from NeuroDebian, the installation will ask you for the location of your Matlab installation, and if you want it to rename some Matlab libraries to fix compatibility issues caused by Matlab. Answer YES to these questions, this is crucial! Otherwise hardware accelerated graphics will likely not work with Matlab later on.

If you installed Matlab after installing Psychtoolbox, or after you have upgraded Matlab to a more recent version you must rerun this Matlab compatibility fixing script via: sudo dpkg-reconfigure matlab-support.

At the end of a successfull NeuroDebian installation, run the script PsychLinuxConfiguration from within Matlab or Octave, and follow the interactive instructions and questions to optimize your Linux system for data collection.

Debian and Ubuntu also provide Psychtoolbox directly from their repositories, but these Psychtoolbox packages are usually very outdated, often years behind versions, and they support GNU Octave only, no Matlab:

The packages in the main Debian and Ubuntu archives only ship with GNU Octave support, hence the package to install is octave-psychtoolbox-3.

In general using the NeuroDebian repo above is more convenient and provides more up to date packages for Octave and Matlab, but the distribution packages will do for a quick test drive, e.g., from within a Live Linux system, booted from a USB flash drive, for quick compatibility testing.

If you choose installation from the distribution directly, bypassing NeuroDebian, after package installation, run the script PsychLinuxConfiguration from within Octave once, and follow the interactive instructions and questions to optimize your Linux system for data collection. You may be able to do without this step for a quick basic test drive or maybe for pure student training without need for high timing precision or precise low-level control of your hardware and special equipment.

The advantage of all the above methods is that third-party dependencies are automatically installed by the package manager.

Subversion-based installation

Alternatively, for the most complete and most recent version of Psychtoolbox, you can perform the regular installation via our DownloadPsychtoolbox.m script. The following will install Psychtoolbox by checking out the Subversion repo to the specified local directory.

  1. If you are using Matlab R2014b or later, go to step 3. For older Matlab versions go to step 2.

    If you are using GNU/Octave on a Debian or Ubuntu based system, execute this command in a terminal: sudo apt build-dep octave-psychtoolbox-3 and then go to step 2. If you are using Octave on a different Linux distribution (unsupported by us, although it will probably work on many!) then you will need to track down and install various runtime dependencies manually.

  2. Install the subversion package from your Linux distribution’s archive (e.g. apt-get install subversion, or yum install subversion, et al.). If you are using Octave, go to step 4. For Matlab, continue to step 3.

  3. On a Debian or Ubuntu based system, quit Matlab, and install the matlab-support package by typing sudo apt install matlab-support into a terminal window. When it asks you for the location of your Matlab installation, tell it. When it asks you if it should rename some Matlab libraries to fix Matlab compatibility issues, answer YES, otherwise hardware accelerated graphics will likely not work later on!

    If the matlab-support package was already installed before you installed Matlab, or after each update of Matlab, run sudo dpkg-reconfigure matlab-support to rerun this fixup script, as described in the previous sentence, othewise hardware accelerated graphics will likely stop to work!

  4. Start your Octave or Matlab, cd into the folder that you saved the DownloadPsychtoolbox.m script in, and run (replace /home/foo/toolbox/ by a folder of your choice!):

    >> DownloadPsychtoolbox('/home/foo/toolbox')

However, Octave mex files from this Subversion download from us, should you choose GNU/Octave, will only work out of the box with with Octave 5.2 and later on Ubuntu 20.04-LTS and later. All required dependencies like GStreamer-1.16+, libdc1394, libusb, libfreenect, etc. need to be manually installed in this case. It may work on Debian/Ubuntu based system to execute “sudo apt build-dep psychtoolbox-3” though to get your distribution to automatically install required dependencies. Generally prefer the NeuroDebian installation instead, if you are on Debian or Ubuntu flavors and don’t need the absolutely latest functionality at the day of release.

Additional tips for installing and using Psychtoolbox on Linux.


Filesystem locations given here are examples. You could choose other disc drives or folders of your liking instead:

  1. Skip this step and go directly to step 2 if you use Matlab R2014b or later, instead of an older Matlab version or of GNU/Octave.

    Download and install the Subversion installer

  2. Download the Psychtoolbox installer to your desktop.

  3. You must install the 64-Bit GStreamer-1.22.5 MSVC or later versions runtime from even if you do not need multi-media support! Do not install the MINGW variant, it will not work, but likely crash! Make absolutely sure that you install all offered packages. Read help GStreamer carefully for this purpose, before downloading and installing GStreamer.

    If you intend to use Octave, you will need to delete the following DLL files from the C:\Program Files\GNU Octave\Octave-7.3.0\mingw64\bin\ folder: opengl32.dll – Otherwise hardware accelerated visual stimulation will not work.

  4. You may also need to install the Microsoft Runtime Libraries for MSVC 2015-2019 if you use Matlab instead of Octave. For a few use cases you may even need those if you use Octave. You can find installers for these at Microsoft’s site beforehand. Otherwise when our installer aborted half-ways, follow the instructions it prints to the console. Or simply click this link to get a copy bundled with Psychtoolbox

  5. Open Matlab as administrative user (right-click the Matlab shortcut and “Run As Administrator”) and type the following in the command window, assuming you want Psychtoolbox to be installed inside the C:\toolbox folder:

    >> cd('into the folder where you downloaded DownloadPsychtoolbox.m to').
    >> DownloadPsychtoolbox('C:\toolbox')

    The second command will take a bit of time (a few minutes in some cases) and may generate a lot of output. Please be patient (and make sure your computer is not going to go onto standby while installing). You may get the command line reappear before the installation is finished - so don’t assume the command line reappearing means that installation has hung. The installer will tell you when it is finished.

    If the download fails, read below on Download Problems.

If you want to know more about the downloader, see DownloadPsychtoolbox (or help DownloadPsychtoolbox in the Matlab command window.)


  1. Skip this step for Psychtoolbox 3.0.17 or later with Matlab R2014b or later. Also skip it with GNU/Octave if you already have HomeBrew installed Go to step 2 instead.

    Otherwise get and install Subversion from somewhere, e.g., HomeBrew.

  2. Download the Psychtoolbox installer to your desktop.

  3. Open Octave or Matlab and type the following in the command window:

    >> cd ~/Desktop
    >> DownloadPsychtoolbox

The second command will take a long time and may generate a lot of output. Please be patient.

If the download fails, read below on Download Problems. If you want to know more, see DownloadPsychtoolbox (or help DownloadPsychtoolbox in the command window.)

  1. If you intend to use multi-media functions, or if you want fast, high-quality, cross-platform, consistent text rendering with Matlab, you must install the 64-Bit GStreamer-1.18.5 or later runtime from Make absolutely sure that you install all offered packages. Read help GStreamer carefully for this purpose, before downloading and installing GStreamer.

After Download and installation

You should now have a complete Psychtoolbox installation. To start learning about the Psychtoolbox, use the help command. For example,

>> help Psychtoolbox will list the categories of functions in the toolbox, and

>> help PsychDemos will list all the demos available.

A PDF file with the presentation slides of an introduction into Psychtoolbox-3: Talk slides of Psychtoolbox presentation, given at ECVP 2013 Bremen

More detailled information can be found in the Psychtoolbox subfolder named PsychDocumentation of your Psychtoolbox installation.

Alternate download as a zip file

If regular installation via Subversion or package respositories does not work for some reason, you can also manually download a zip file which contains a given Psychtoolbox release, including the source code. These downloads are larger due to inclusion of the source code.

Click this link to go to the downloads page for all official releases.

Then read on in the following section on how to set up your manually downloaded copy of Psychtoolbox.

Installation without Download

Note: You still need to execute operating-system dependent or Matlab/ Octave dependent setup steps like installing GStreamer, or other packages and configuration steps mentioned above. Essentially do everything that doesn’t directly relate to execution of DownloadPsychtoolbox or installation of Subversion before proceeding here.

If you already have downloaded a copy of the Psychtoolbox folder onto a local computer and want to replicate that installation onto other computers, then you don’t need to download the toolbox again. Instead, simply copy the Psychtoolbox folder to the other target machines. Next, startup Matlab or Octave on that machines, change Matlab’s or Octave’s working directory to the copied Psychtoolbox folder (cd command) and then type SetupPsychtoolbox (see SetupPsychtoolbox or type help SetupPsychtoolbox). The SetupPsychtoolbox script will setup your copied local Psychtoolbox folder for use with Matlab or Octave, just as our installers would do. This procedure can save some download time.

If you cannot install the Subversion client svn for some reason and can not use Matlab R2014b or later with its integrated svn client, then you can also download the ZIP file comprising the whole project. Running SetupPsychtoolbox from the Psychtoolbox sub-folder from the extracted ZIP will add PTB to your Matlab or Octave path.

Staying Up-to-Date

If you installed Psychtoolbox-3 for Linux from NeuroDebian, Debian or Ubuntu, your operating system will automatically notify you of new Psychtoolbox releases. After your approval, it will automatically upgrade the toolbox to the new version.

After a manual installation on OSX, Windows or Linux via DownloadPsychtoolbox, Psychtoolbox-3 can be updated to the latest version by typing the following command:

>> UpdatePsychtoolbox

For more information, see UpdatePsychtoolbox or type help UpdatePsychtoolbox inside Matlab.

More Information

Download problems

You can also download Psychtoolbox as a zip file.

If the installer complains about not being able to find the Subversion client “svn” because it is installed in an unusual location, you can try to locate the client yourself on your filesystem by use of your operating systems search functions and then add the path to the folder which contains the “svn” executable to your Matlab or Octave path. E.g., if the svn client is found under /opt/local/bin/svn, do a addpath('/opt/local/bin') in Matlab or Octave, save the path via savepath and then retry.

Sometimes the downloader fails with a message like “Command CHECKOUT failed with error code xxx” with xxx being some number, followed by a description of the error condition. You may see any of these, or similar messages referring to the network or connections …

svn: Can't connect to host '': A socket operation was attempted to an unreachable network.
svn: PROPFIND of '/svnroot/repos/osxptb/unsupported/Psychtoolbox': could not connect to server (
svn: Connection timed out ...
svn: Connection refused ...

This can mean two things:

Subversion server is down
… our Source code repository server on or part of your internet connection is experiencing temporary problems. Don’t panic, just wait a couple of minutes (sometimes a couple of hours) and retry.
Subversion server cannot be reached due to a network `proxy` or `firewall`
Your institution might route all web traffic trough a local proxy server, which can interfere with the operation of Subversion because it also uses HTTP to check-out the Psychtoolbox from the repository. See FaqDownloadFails to learn how to teach svn to use your institution’s proxy.

If the updater fails with a message like …

svn: E155036: Please see the 'svn upgrade' command 
svn: E155036: Working copy '/opt/MATLAB/R2022b/toolbox/Psychtoolbox' is too old (format 10, created by Subversion 1.6) 

… then open a terminal window, cd into the Psychtoolbox folder and then run the command svn upgrade. Then rerun the UpdatePsychtoolbox command.

Alternatively, if you haven’t made any modifications to your Psychtoolbox folder, simply rerun DownloadPsychtoolbox to install a fresh copy of Psychtoolbox.

If you need timely expert support in resolving download or installation issues, we also offer paid support under this link. If everything else fails, contact the Psychtoolbox forum with a description of what you tried.


Installing Psychtoolbox-3 requires Subversion because the toolbox is now kept in a database, which is stored on a publicly accessible Subversion server. The database both stores the latest version of the code and tracks all of the changes that have been made to it. This simplifies maintenance and development of the toolbox. The Psychtoolbox functions DownloadPsychtoolbox and UpdatePsychtoolbox automate interactions with the database, so you never have to use Subversion directly. To learn more about Subversion, you can visit the website:

Matlab R2014b and later include a builtin Subversion client, whereas if you use earlier versions of Matlab or you use Octave, you will need to install a 3rd party Subversion client yourself, as described above in step 1 of the download instructions.


If you find something broken after an update, then you might want to revert to an earlier version. The UpdatePsychtoolbox script allows you to downgrade to an earlier version of Psychtoolbox. To downgrade to the previous version, type this into the command window:

>> UpdatePsychtoolbox(PsychtoolboxRoot, 'PREV')

You can repeat this step to incrementally downgrade to earlier versions.

If you know the revision number of a specific Psychtoolbox release, because you noted down the output of PsychtoolboxVersion to document the software version you used to conduct some of your studies, then you can get that version as well, by passing that revision number instead of ‘PREV’. E.g., to get software revision 1236, type

>> UpdatePsychtoolbox(PsychtoolboxRoot, '1236')

Access to Archived Versions of PTB-3

You can also choose to install specific old versions of Psychtoolbox-3 by providing their name instead of ‘current’ or ‘unsupported’. E.g., to download Psychtoolbox-3.0.12 you would run DownloadPsychtoolbox([], 'Psychtoolbox-3.0.12'). A list of older versions can be found at the bottom of the page found here. This only works for versions since 3.0.10.