Visual hullucinations

Hi

Does anyone else experience visual hullucinations?

My brain and visual system do this weird thing where they take a collection of objects and merge them into something new.... Like a tree a street sign and a flower box suddenly become a donkey..... 

Most of the time it is so ridiculous I know it is happening but at other times it is more challenging like i might see a person bending over, and I wonder what is wrong so if I am on my bike I will turn back to see if they are OK only to realise it was just a Bush and a dustbin... 

This tends to happen when I am more stressed.... 

Can anyone help?