Psychtoolbox-3 Download, Installation, and Update

In order to install and use the Psychtoolbox, you must already have Matlab or Octave installed on your computer. If you already have Matlab or Octave installed, start it up and read on.


  1. Removing Old Versions of Psychtoolbox
  2. Installation Instructions
  3. Installation without Download
  4. Staying Up-to-Date
  5. More Information
    1. Download Problems
    2. Subversion
    3. Downgrading


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, remove it by following the instructions in the next section, Removing Old Versions of Psychtoolbox.
  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 filesystem 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.

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. See the System Requirements.

1. Download Subversion installer

2. Install Subversion by double-clicking on the installer downloaded in Step 1. Run the installer and select all the default options.

3. Download the Psychtoolbox installer to your desktop. You do this by right-clicking on the link with your mouse, then select "Save link target as..." or "Save linked file" or however this is called in your webbrowser.

4. Read the instructions relevant to your operating system below.


Open Matlab and type the following in the command window:
>> cd ~/Desktop
>> DownloadPsychtoolbox

The second command will take a long time and 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 Matlab command window.)


Psychtoolbox for Linux is available either from us directly for computers with Intel compatible processors, or via the NeuroDebian repository for neuroscience software for Intel compatible computers running a Debian or Ubuntu Linux distribution or a derivative thereof. It is also available as part of the "testing" and "unstable" branches of Debian GNU/Linux as well as Debian 7 for various non-Intel processors, e.g., PowerPC, ARM, MIPS, Sparc, IBM S/390. NeuroDebian provides installation instructions on its website. Ubuntu 12.10 also provides Psychtoolbox as part of the operating system. Debian and Ubuntu 12.10+ provides Psychtoolbox via the standard apt/dpkg software management system under the name "psychtoolbox-3". If you use a Debian or Ubuntu Linux distribution, NeuroDebian or Debian provide the most convenient method of installing Psychtoolbox and keeping the software up to date. The default installation from these sources will only provide GNU/Octave support. Run the script DownloadAdditionsForNeuroDebian from within Matlab after the installation for octave to install the Matlab versions as well.

If you want to install from our own repository, e.g., because you use a different Linux distribution or just like to install directly from us, then the following will work:

Assuming you wanted to install Psychtoolbox inside the folder /home/foo/toolbox/, you would type:
>> DownloadPsychtoolbox('/home/foo/toolbox')

Additional tips for installing and using Psychtoolbox on Linux can be found under UsingPsychtoolboxOnLinux.


    1. Open the My Computer icon (it is either on the desktop or in the Start Menu).
    2. Double-click on the C: drive icon.
    3. Create a new folder called toolbox. This assumes you want to install into the toolbox folder.
    4. Move the Psychtoolbox installer (DownloadPsychtoolbox) from the Desktop to the new toolbox folder.
    5. If you want to use the 64-Bit Psychtoolbox for 64-Bit Matlab, you must install the 64-Bit GStreamer SDK from, otherwise Psychtoolbox will not work and the installation will abort.
    6. You also need to install the Microsoft Runtime Libraries for MSVC 2010. You can find installers for these at Microsofts site or, after the download completed, but the installer aborted half-ways, follow the instructions of the installer.
    7. Open Matlab as administrator (for Windows 7, right-click Matlab shortcut and Run As Administrator) and type the following in the command window:
>> cd C:/toolbox
>> DownloadPsychtoolbox('C:/toolbox')

The second command will take a long time (~10 min in some cases) and 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, see DownloadPsychtoolbox (or help DownloadPsychtoolbox in the Matlab command window.)

You should now have a complete Psychtoolbox installation. Occasionally type the command UpdatePsychtoolbox in the Matlab command window: this will ensure that you have the latest version of Psychtoolbox. 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 and the differences to Psychtoolbox-2:
Talk slides of Psychtoolbox presentation, given at ECVP 2007 Arezzo

Class notes for beginners can be found at:

Installation without Download

If you already have downloaded a copy of the Psychtoolbox folder onto a local computer and want to replicate that installation onto other computers 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 safe some download time.

Staying Up-to-Date

Psychtoolbox-3 can be updated to the latest version by typing the following Matlab command:

>> UpdatePsychtoolbox

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

More Information

Download problems

If the installer complains about being not 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:
  1. 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.

  2. 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 institutions proxy.

If the updater fails with a message like ...
svn: E155036: Please see the 'svn upgrade' command
svn: E155036: Working copy '/opt/MATLAB/R2011b/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 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 Subversion database, which is stored on a publicly accessible 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:



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 in the Matlab command window:

>> UpdatePsychtoolbox(PsychtoolboxRoot, 'PREV')

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

Access to Archived Versions of PTB-3

You can also choose to install specific old versions of PTB-3 by providing their name instead of 'current' or 'unsupported'. E.g., to download Psychtoolbox-3.0.6 you would run DownloadLegacyPsychtoolbox([], [], [], 'Psychtoolbox-3.0.6'). A list of older versions can be found at the bottom of the page found here. Version 3.0.10 and later use the DownloadPsychtoolbox function instead of DownloadLegacyPsychtoolbox.
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