"And why do you call it 'perception'? Because it perceives, thus it is called 'perception.' What does it perceive? It perceives blue, it perceives yellow, it perceives red, it perceives white. Because it perceives, it is called perception.
"And why do you call them 'fabrications'? Because they fabricate fabricated things, thus they are called 'fabrications.' What do they fabricate as a fabricated thing? For the sake of form-ness, they fabricate form as a fabricated thing. For the sake of feeling-ness, they fabricate feeling as a fabricated thing. For the sake of perception-hood... For the sake of fabrication-hood... For the sake of consciousness-hood, they fabricate consciousness as a fabricated thing. Because they fabricate fabricated things, they are called fabrications. 
"And why do you call it 'consciousness'? Because it cognizes, thus it is called consciousness. What does it cognize? It cognizes what is sour, bitter, pungent, sweet, alkaline, non-alkaline, salty, & unsalty. Because it cognizes, it is called consciousness.
http://www.accesstoinsight.org/tipitaka ... .than.html
I always thought that consciousness is label as mere observer or receiver but this sutta interpret it differently, now i'm confuse of the true meaning between consciousness and perception.
Appreciate any help.