Silencing demonstrates the tight coupling of motion and object appearance. Simply by changing the retinotopic coordinates—moving the object or the eyes—it is possible to silence awareness of visual change, causing objects that had once been obviously dynamic to suddenly appear static.

References:

  Suchow & Alvarez (2011) Motion Silences Awareness of Visual Change. Current Biology 21, 140–143

Original demos:

https://visionlab.harvard.edu/silencing/

Here is the math behind the basic element of the stimulus, a superellipse shape:
  
    random = pseudorand(i, 1111)
    se = 0.5+1.5*(1+cos(shapemod+2*pi*random))/2
    super = pow(abs(x/radius),se)+pow(abs(y/radius),se)
    carrier = super>0.75 & super<1
    z = carrier/2-0.5

This element is then replicated at different positions (x_i, y_i) and modified according to:

  shapemod = 2*pi*time*chspeed
  dirmod = sin(2*pi*time*rotspeed/120)*rectanglewave(time,2*period,0,0.5)
  nbc = 12
  for i = 0 : 47
    ecci = 1.5*radius*(6+floor(i/nbc))
    anglei = dirmod*pi/6+2*pi*i/nbc+(pi/nbc)*mod(floor(i/nbc),2)
    x_i = ecci*cos(anglei)
    y_i = ecci*sin(anglei)
    

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 !