This kind of stimulus is typically used to explore the center-surround interactions mediated by cortical lateral connectivity in the early visual cortical areas which are thought to be impaired in individuals with schizophrenia for example because they are less prone to visual contextual effects.

References:

  Tadin et al (2006) Weakened Center-Surround Interactions in Visual Motion Processing in Schizophrenia. The Journal of Neuroscience 26(44):11403–11412


  Butler et al (2008) Visual Perception and Its Impairment in Schizophrenia. Biol Psychiatry. 64(1):40–47


  Chen et al (2008) Altered center-surround motion inhibition in schizophrenia. Biol Psychiatry. 64(1):74–77


  Yoon et al (2009) Diminished Orientation-Specific Surround Suppression of Visual Processing in Schizophrenia. Schizophrenia Bulletin 35(6):1078–1084

Here is the math behind this stimulus:

 lp = pnoise(x/scale+time*speed,y/scale)      # Isotropic lowpass noise
 hp = pnoise(2*x/scale-time*abs(speed),y/(5*scale)) # Oriented highpass noise
 s = r<radius                     # Surround envelop
 c = 1-hsmoothstep(r,radius/2,sigma)       # Center with smooth border
 z = lp*s*(1-c)+hp*c                 # Final composing

The whole stimulus is generated in real-time using a GLSL shader that runs right inside your WebGL-compatible browser. The plain Math behind the stimulus was converted to this optimized GLSL shader using the new Psykinematix Pro Edition. Translation to Matlab and Python code is also possible !

This whole widget was also fully generated using Psykinematix Pro Edition. The parameters that control the stimulus properties through the sliders are the same as the ones you would define as dependent or independent variables when using the stimulus in an actual psychophysical experiment run in Psykinematix. The widget creation is otherwise fully customizable with your own logo, copyright, links, etc.

To learn more about the widget creation, click on the above "Made With" button !