This is just so wrong on many levels.
To begin with, size of the animal has no correspondence whatsoever with its cognitive abilities. With that logic, an elephant would be way, way more intelligent than your good self.
(Behave at the back!
)
Likewise, neither brain size, nor the proportion of the brain to the rest of the body should be taken as any indication. We have one brain, but there are creatures with several and each can act independently or in unison with others.
As a species, our arrogance is unlimited when it comes down to measuring our fellow creatures and we insist on comparing them to our allegedly brilliant selves.