What Do You See?

[Boy]

I see the black blob -- or hole -- against the magenta background expanding the fastest and the slowest against the red background.

[Boy]

This is what the NYT says about it:

"Does the picture you see above appear to be moving, growing or expanding? This static image, of a darkness that threatens to swallow up the viewer, has much to teach us about how our brains and eyes see the world.In a study published last week, psychologists tested this illusion on 50 men and women with normal vision. Using an infrared eye tracker, they found that the greater a participant’s response to the illusion, the stronger the pupil dilation response. About 14 percent of people can’t see the illusion at all.
Your pupils unconsciously adjust to the light in your surroundings, dilating to capture more light in darkness and constricting to prevent overexposure in brightness. When you look at this illusion, the hole is not darkening. But the perception of the hole darkening is enough to make your pupils respond.
The researchers hypothesize that the illusion works because the gradient on the central hole makes it look as if the viewer is entering a dark hole or tunnel, prompting the pupils to dilate.
One hypothesis is that the brain is trying to predict and show us the future in order to perceive the present, a result of the brain’s strategy to navigate an uncertain, ever-changing world. The brain adapts by, say, prompting pupils to dilate when anticipating darkness."

[Boy]

A reader posted a comment with a link to the opposite illusion: https://seniorjunior.blogspot.com/20...-illusion.html

[handrawn]

afraid I fall into the 14%, which is better than falling into a black hole I guess - I think I can see a very faint shimmer, but it is so faint I am not sure

I am slightly astigmatic, that might be a factor

[handrawn]

ok I got a partial result by changing the way I look at it - stare straight at it then move my eyes quickly to one side so it is on the edge of my vision - the illusion may be a function of the visual switch:- from viewing with the centre of the retina which is more sensitive to colour and detail, to the edges which are more sensitive to changes in light intensity