In my view this illusion is totally mind-boggling.
We all know how Ponzo illusion works, in case you don't, The Ponzo illusion is an optical illusion that was first demonstrated by the Italian psychologist Mario Ponzo in 1913.
He then suggested that the human mind judges an object’s size based on its background but in this particular example it’s really hard to settle that both red lines are exactly the same - I measured them and you should too. Still, I can’t deal with the fact that the further line isn’t little bolder and little longer. Can you convince yourself? How can “what we see” and “what our mind is telling us” exist in harmony?