Optical illusion of four blinking dots divides viewers

An optical illusion posted to Reddit is dividing the internet.

At first, the graphic appears to simply be four blinking dots. On closer inspection, there are actually a variety of movements the dots could be making.

To some. the dots appear to be oscillating from right to left but others see them moving up and down.

 However, others see the dots as rotating around one another. 

‘What’s fun and interesting to try is to see if you can see both directions without altering screen position or holding your hand in front,’ one user said online. 

‘Took me a few tries. I only saw vertical, then could see horizontal, then could jump between.

‘All I see are two vertical dot oscillator,’ another person countered. 

‘I have to stick my finger in between as a horizontal line to make them horizontal.’

At altered speeds, the illusion also appears different.

In a slower version, it is easier to see all the different movements the dots could be making.

In a sped up frame, the dots almost appear to simply be blinking (which is almost a relief to the eyes!). 

The illusion is a variation of the stroboscopic effect, when a a moving object is represented by a series of short samples distinct from a continuous view.

Adjusting the ‘strobe frequency’, or speed in which the dots move, can change the way we see the illusion.  

To some the dots appear to be oscillating from right to left but others see them moving up and down