Illusion?

Question (genuine): Why does this graphic create an illusion?
As people will pick up, these rectangles are all the same size, created with the blend tool. I have always wondered why it is that visually we see it differently. Also, from a perspective point of view you would think that we would see it in reverse, the first rectangle would appear larger and then they would diminish towards the back. As you can see I have never studied graphics or art, I am just someone who loves to play with X4, I actually bought the programme for photo modification and became a real fan of all the other aspects (as I learn them) of this fantastic programme. Thanks.
Rupert

Hi Rupert,

I'm not sure I know the answer to your question. However that will not stop me from trying to answer. ;):D

I think the lack of perspective tricks the mind into seeing the back rectangle as being larger than the front rectangle.

As you say, your mind is tricked by the lack of perspective into assuming that the back rectangle must be larger.