Psykinematix follows an intuitive design paradigm based on the Method / Procedure / Stimulus logic.
With this simple hierarchical structure in mind and since no programming is required, implementing standard experimental protocols is effortless, and building new experiments from scratch takes only minutes. Using Psykinematix' design wizard it is even easier to create "canned" experiments.
Any experimental property can be specified using either an independent or dependent variable or even a mathematical expression, and it is easy to run multiple interleaved conditions.
There are several editions available, all of them shared the functionalities described below.
WHAT CAN PSYKINEMATIX DO FOR YOU ?
Psykinematix provides a complete streamlined workflow to carry out psychophysical experiments, from calibration of the stimulation display to data fitting.
New or standard psychophysical protocols can be designed rapidly and accurately using its Method / Procedure / Stimulus intuitive logic.
Complex stimuli can be generated without any OpenGL or programming knowledge.
DOWNLOAD THE OFFICIAL BROCHURE (.pdf) |
STREAMLINED DISPLAY CALIBRATION
While display calibration is often seen as a cumbersome process, it is a critical step which should not be skipped because it could affect your study replicability !
Display calibration is a breeze with Psykinematix: it offers an easy-to-use and fast process to calibrate the geometry, luminance and color of your display. Reminders can be set to perform the calibration at regular intervals, and Psykinematix has built-in support for several commercial colorimeters you can use for both luminance and color calibration.
If there is one device we would recommend, it is the low-cost Spyder 5 Express colorimeter from DataColor. Their latest SpyderX is also supported in the new 64-bit Editions of Psykinematix.
SIMPLIFIED DESIGN OF EXPERIMENTAL PROTOCOLS
AN INFINITE SELECTION OF VISUAL STIMULI
Psykinematix has built-in support for a large variety of simple and complex stimuli:
- basic shapes
- grating-based stimuli
- checkerboard-based stimuli
- custom Ishihara plates
- multi-element stimuli
- multimedia stimuli (text, image, sound, and movie)
NO PROGRAMMING REQUIRED, JUST USE PLAIN MATH !
For example, to generate this D4 radial modulation stimulus (based on Wilkinson, Wilson & Habak, 1998), you simply enter in Psykinematix the same equations that you find in the publication:
radmod = radius*(1+ram*sin(rf*theta+phase))
ar = abs(r-radmod)/sigma
z = (1-4*(ar^2)+4*(ar^4)/3)*(e^(-(ar^2)))
radmod = radius*(1+ram*sin(rf*theta+phase))
ar = abs(r-radmod)/sigma
z = (1-4*(ar^2)+4*(ar^4)/3)*(e^(-(ar^2)))
Psykinematix automatically checks and analyzes each sub-expression, recognizes the 2D spatial parameters x, y, r and theta, converts all parameters into proper units (highlighted in blue) and optimizes the evaluation of the whole expression. There is virtually no limit to what you can do with this powerful Psykinematix' feature: for instance, you can use convolution, Fourier transform, and noise generation functions as well. You can even import color images as 2D variables and applied on them any custom filtering operation.
To generate a time-varying stimulus, you simply use the time variable in your expressions. For instance to create this motion-contrast modulated noise stimulus (based on Watson and Eckert, 1994), you only have to enter these 5 lines :
c1 = pnoise(x,y+speed*time)
c2 = pnoise(x/4,y/4-speed*time)
m1 = sqrt(0.5*(1+m*sin(2*pi*fm*y)))
m2 = sqrt(1-m1*m1)
z = c1*m1+c2*m2
c1 = pnoise(x,y+speed*time)
c2 = pnoise(x/4,y/4-speed*time)
m1 = sqrt(0.5*(1+m*sin(2*pi*fm*y)))
m2 = sqrt(1-m1*m1)
z = c1*m1+c2*m2
While the Standard Edition of Psykinematix does a decent job to optimize the generation of time-varying stimuli (by skipping duplication for instance), the new GPU Edition of Psykinematix alleviates all these problems by translating and compiling the mathematical description you provide for your stimuli into a shader program that runs directly on the GPU (Graphics Processing Unit) of your graphics card.
This results in full-screen stimuli generated in real-time, and this is totally automatic and transparent to the user ! The GPU Edition can even modulate the visual stimuli with variable parameters provided in real-time by some external equipment.
IT NEVER HAS BEEN SO EASY TO CREATE COMPLEX STIMULI !
All stimuli created in Psykinematix can be combined spatially and temporally, for example combined into first- or second-order stimuli, sequenced according to a timeline with SOA and ISI between them, or interleaved at a precise temporal frequency.
How local parts are integrated into global features is a central question in the study of visual perception, and Psykinematix provides 3 specific manners to duplicate many micro-elements that need to be temporally or spatially integrated to form global stimuli, again with no programming required:
- random-dot kinematograms (RDK) to study motion integration for instance,
- multi-element fields (MEF) to study visual search for instance,
- sampled-shape stimuli (SSS) to study contour integration for instance.
RDKs are useful stimuli to study motion integration. They are however often limited to simple dots with ill-defined properties. With Psykinematix, any stimulus can be used in RDKs. This example shows the use of well-defined micro-elements (radial Gabors) to create a heterogeneous chromatic random-dot kinematogram composed of rotating high frequency achromatic micro-elements, expanding medium frequency isoluminant red-green micro-elements, and translating low frequency blue-yellow micro-elements.
Search tasks often use multi-element visual displays with one or few targets among many distractors. With Psykinematix, the target can be made of spatially and temporally correlated micro-elements as shown by this example that takes advantage of its multi-element field (MEF) and sampled- shape stimulus (SSS) facilities: a circular contour is embedded in a field of randomly oriented Gabor patches where all micro-elements rotate at the same speed either clock-wise or anti-clockwise, and the contour elements get aligned only for a fraction of a second.
This snake versus ladder configuration is another example of multi-element visual displays easily generated with Psykinematix. Fields of Gabor patches are often used to investigate psychophysically contextual effects thought to result from lateral interactions in the early visual cortical areas. Contour integration is one of those tasks that promote figure-ground segregation based on several Gestalt principles such as proximity, similarity, good continuation and closure. The precise manipulation of the local properties can help study how global processing emerges from the integration of local features.
ENHANCED LUMINANCE/CONTRAST RESOLUTION
Most computers have their graphics subsystem limited to an 8-bit representation (or 256 levels) of each chromatic component (red, green, blue) that encodes the appearance of each pixel in a visual stimulus. This limited resolution in luminance and contrast would normally prevents the use of off-the-shelf computers for measuring achromatic and chromatic contrast thresholds without additional specialized hardware. However Psykinematix implements several software-only techniques to enhance luminance/contrast resolution (e.g. spatial dithering, bit-stealing, or noisy-bit) that alleviate the hardware limitation.
In collaboration with Kenzo Sakurai from Tohoku Gakuin University in Sendai, we recently compared these solutions when assessing contrast sensitivity with different display technologies, and you may be surprised by the results:
MAXIMUM COMPATIBILITY !
Most Editions of Psykinematix are now available as Universal versions, hence providing full compatibility from macOS 11 ("Big Sur") to the latest macOS 14 ("Sonoma") for both Intel-based and Apple M-Series Macintosh computers. If you have not upgraded your Macintosh computer to "Catalina" or above yet, see our recommendations before deciding. However there is no need to purchase the latest Macintosh computer or perform unnecessary upgrade of your macOS operating system if you don't have too: Psykinematix is compatible with all versions of macOS since Mac OS X 10.4 and all Macintosh computers released in the past 15 years including the PowerPC and Intel 32-bit architectures †.
† PowerPC compatibility for the 32-bit Standard/Student Edition only. All other Editions support the Intel architecture, from Mac OS X 10.6 to macOS 10.14 (Mojave) for the 32-bit version, and from Mac OS X 10.7 to the latest macOS 14 (Sonoma) for the 64-bit version. Apple M-Series architecture (M1, M2, and M3) is also supported from macOS 11 ("Big Sur") to the latest macOS 14 ("Sonoma").
SCREENSHOTS !
Get another glimpse of Psykinematix functionalities through these screenshots (or you can browse the whole documentation here):