Originally Posted by jokergirl

That depends a little on your definition of perception.
In spacetime, there are four dimensions, so any aliens sharing this spacetime would be moving in them. There might be beings that are not bound to these dimensions, but those would be so alien and outside our universe we could probably not understand them (think dimensionless energy being, or parallel universe there - or the mice in HHGTTG who are according to themselves just "the translation into our spacetime of multidimensional hyperintelligent beings").

"Seeing" in itself is a highly specialised function. Humans see threedimensional information in an angle determined by the relative position of our eyes, in a very limited electromagnetic spectrum that is for some reason interesting to us.
Most animals on the planet "see" differently - few have true threedimensional perception (think of the position of the eyes on horses, whose perceptive angle only overlaps in a tiny fraction) and many perceive different spectrums or different information than us - for example, it was long believed that many land animals only could perceive motion, the delta of one picture to the other in the time dimension. I think it has since been disproven though.
We also can't move our eyes truly independently and perceive two channels of information at the same time (think chameleon). Niven's Puppeteers had two "heads" with sensor nodes on each that could either perceive two streams or be used for triangulation.
And how would you classify other dimensions of perception, like the ultrasound mapping of bats or the electrical perception of fish?

Lots of ideas for interesting aliens...