Psychtoolbox 3.0.22.3 "The most fantastic Matala" 🍹

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Psychtoolbox 3.0.22.3 “The most fantastic Matala” was released on 14th August 2026.
… A last act of work from a greek island before it is :beach_with_umbrella: time, so the brain can calm down and go into full vacation mode. :spiral_shell:

You can download it as a zip file from the following link:

https://github.com/Psychtoolbox-3/Psychtoolbox-3/releases/download/3.0.22.3/3.0.22.3.zip

The complete development history can be found in our GitHub repository.
The release tag is “3.0.22.3”, with the full tree and commit logs under the URL:

https://github.com/Psychtoolbox-3/Psychtoolbox-3/tree/3.0.22.3

Compatibility changes wrt. Psychtoolbox 3.0.22.2:

  • Be reminded that macOS 26 Tahoe is currently not recommended for use with
    Psychtoolbox, due to severe Tahoe operating system performance bugs, caused
    by Apple and only fixable by Apple. These bugs will affect any software that
    tries to achieve robust, reliable, trustworthy and accurate visual stimulus
    presentation timing and timestamping. It causes framerates to be cut in half!
    Only software with broken timing support will not suffer this degradation, iow.
    to my knowledge all other toolkits in existence. This is the situation as of
    macOS 26.0 - 26.2, the status of current macOS 26 and later is unknown to myself.
    The same applies to upcoming macOS 27 Golden Gate.

Highlights:

  • None. Mostly lots of bug fixes and smaller feature work and refinements. Most
    of the work done in the last months is “behind the scenes” work, preparing
    for the future, but not yet visible to users in the form of new features or
    obvious improvements, beyond what is listed here.

All:

  • Improvements to OpenXR handtracking for VR applications. We can now make use
    of the XR_FB_HAND_TRACKING_AIM extension on VR devices that support it, to
    detect, and report properties of, “aim” gestures made by users.

  • Procedural noise: Update (classic) Perlin noise to latest version.
    The functionality is demonstrated by ProceduralNoiseDemo(), now better!

    There were some changes in the upstream shaders circa 2021 that
    appear to visibly improve randomness/reduce banding artifacts. There
    may also be a minor performance improvement because some math was simplified,
    but may be system-dependent (I only saw 10s of microseconds changes).
    Contributed by Alex Forrence.

  • GetGITInfo: Make simpler and more robust. Contributed by Alex Forrence.

  • VBLSyncTest: Suppress beamposition plots on beamposition-less systems harder.

  • Some improvements to the PsychColorimetric functions by David Brainard, as
    usually poorly documented in his non-conformant commit messages, so I won’t
    give details. Except: “Added CarrollNeitzNomogram and test.” and “Moved in
    routines from BrainardLabToolbox.” Other new functions seem to be
    TransmissionToOD, ODToTransmission (OD ~ Optical density?), “StockmanRiderNomogram”
    and “StockmanRiderNomogramDemo”, and “PhotopigmentNomogramDemo”.

  • Various other smaller refinements, bug fixes and documentation updates. Various
    internal work in the software, not obviously user visible yet.

Linux:

  • Psychtoolbox was built against Matlab R2026a and Octave 6.4 under
    Ubuntu 22.04.5-LTS. It only works on Ubuntu 22.04-LTS and later.

  • RaspberryPi OS 13 is now usable with Psychtoolbox again, after my bug fixes
    for graphics driver bugs were accepted and integrated into it. RaspberryPi OS 12
    suffered the same severe performance bugs, but the bug fixes were not applied to
    it, as the RaspberryPi foundation considers OS version 12 end-of-life. This leaves
    OS 11 and 13 as the supported versions for Psychtoolbox, but I will probably soon
    remove support for OS 11 as well. So upgrading to RaspberryPi OS 13 is recommended.

  • Add a hack to allow basic HDR-10 mode on RaspberryPi 4 and later, with
    a very custom software stack: Mesa zink OpenGL driver from Mesa 25.1 or
    earlier, e.g., Mesa 25.0.7 from RPi OS 13, combined with a Mesa v3dv Vulkan
    driver from Mesa 25.3.0 or later. Also supports very slow HDR movie playback
    at ~5 fps for 4k HDR-10 content. Given the complexity of the setup needed,
    this is more of a “can pigs fly?” proof of concept at the moment, not something
    that just works out of the box plug & play.

  • PsychOpenHMDVR: Fix it by fixing abuse of ‘clear Screen’ with a new method.
    Turns out this was broken quite a while. The fact I didn’t notice earlier, and
    nobody else complained, suggests there aren’t any users of this driver. Not
    surprising, given the auto-selected default driver is OpenXR, which is superior
    in almost any sense. We should probably just retire this driver.

  • MultiWindowVulkanTest: Refine further for more stress testing.

Windows:

  • Psychtoolbox was built against Octave 7.3 under Windows 10.

  • Due to a lapse in our Matlab licenses, the mex files have only been updated for
    Octave, whereas the files for Matlab stay the same as in Psychtoolbox 3.0.22.2.

  • PsychStartup: Fix GStreamer SDK root definition on MS-Windows better.
    Use fullfile() for building final path to GStreamer bin directory, based on sdkroot.

    Apparently, for unknown reasons, on some MS-Windows systems, the getenv()
    call returns a sdkroot without a trailing path separator backslash, whereas on most
    systems it does. Go figure! Lacking a trailing backslash caused the naive [sdkroot ‘bin’]
    concatenation to generate an invalid path. fullfile() deals with this quirk.

    Root of the problem found out, and fix proposed, by our GitHub user @HuwSwan
    in GitHub issue #669 , thanks!

macOS:

  • Psychtoolbox was built against Octave 10.2.0 from HomeBrew on macOS 13.7.8 Ventura
    final update for Intel Macs, and on macOS 15.7.7 Sequoia with Octave 11.1.0 for
    Apple Silicon Macs. The minimum required version of macOS for use of the Vulkan
    display backend, ie. for HDR support on Intel Macs, is now macOS 11.

  • Due to a lapse in our Matlab licenses, the mex files have only been updated for
    Octave, whereas the files for Matlab stay the same as in Psychtoolbox 3.0.22.2.

  • Eyelink mex for 64-Bit Octave on macOS for IntelMacs fixed, and reverted to a
    over 18 months older version for Matlab. Turns out that Eyelink support was broken
    since over 1.5 years on macOS for IntelMacs without anybody noticing or complaining!
    The brokeness was due to IntelMac compatibility bugs in SR-Researchs older Eyelink SDK
    versions used for building the mex file. The bug is fixed in recent SDK’s.

    This gives an indication about how few users with demanding use cases are left on
    Intel based Macs. Our statistics suggest that less than 7% of all paying macOS users
    are still using IntelMacs. Both the drastically reduced number of users, and the
    increasing difficulty in maintaining macOS Intel versions, with all software vendors
    reducing or cancelling support, means that the days of Psychtoolbox on Apple IntelMacs
    will probably be limited. Apple’s next macOS 27 will no longer support IntelMacs,
    Matlab R2026a and later don’t support them, and Homebrew as provider of Octave also
    is announcing a phase out likely towards end of this year.

Enjoy!