The “twinkle goes" effect is a new illusion of extrapolation by Nakayama & Holcombe (2020). The revolving discs disappear when they're horizontally aligned. But in the half of the animation where the disappearance is followed by twinkle (dynamic noise), the discs appear shifted in the direction of motion.

The new study suggests that the illusion is enabled by the dynamic noise masking the offset transients that otherwise accompany an objectʼs disappearance. While this result is consistent with an anticipatory process that pre-activates positions ahead of the objectʼs current position (anticipatory extrapolation theory), an alternative account is proposed based on a continuation of attentional tracking after the object disappears: in the absence of offset transients (masked by the dynamic noise), attentional tracking keeps moving for several tens of milliseconds after the target disappearance, causing the moving object to be perceived at the position of attention.

References:

   Nakayama & Holcombe (2020) Hallucination of moving objects revealed by a dynamic noise background. Preprint, bioRxiv 2020.08.21.262170

   Maus & Nijhawan (2008) Motion extrapolation into the blind spot. Psychological Science 19(11):1087–1091

Here is the math behind this stimulus:

  radius = scale*sep/2
  dirtmod = squarewave(time,8)*2-1
  disktmod = squarewave(time,2)
  backtmod = rectanglewave(time,4,0.75,dynduration/400)
  staticdynoise = unoise(x,5*backtmod*time,8)
  phi = dirtmod*speed*2*pi*time
  xpos = (sep/2)*cos(phi)
  ypos = (sep/2)*sin(phi)
  xpos1 = x-xpos; ypos1 = y-ypos
  disk1 = (xpos1*xpos1+ypos1*ypos1)<radius*radius
  xpos2 = x+xpos; ypos2 = y+ypos
  disk2 = (xpos2*xpos2+ypos2*ypos2)<radius*radius
  rotatingdisks = disktmod*(disk1 + disk2)
  targets = rotatingdisks+(1-rotatingdisks)*staticdynoise
  fixation = r<10
  redfixation = 0.5*float(r<5)
  greyfixation = fixation/2
  stimulus = targets*(1-fixation)
  zr = stimulus+greyfixation+redfixation
  zg = stimulus+greyfixation-redfixation
  zb = stimulus+greyfixation-redfixation

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 automatically 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. The widget creation is otherwise fully customizable with your own logo, copyright, links, etc.

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