Would aliens have the same 3-d perception as we do?

Or would they see the other dimensions also?

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...

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[Foot mouth in put]
Si tacuisses, philosophus mansisses.

We naturally perceive 3 dimensions.

Sometimes I perceive dementia.

Actually, we naturally perceive 2 dimensions, and wring out the third with signal processing and triangulation.

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I know what you are saying but I am not sure that I agree with your wording.

We perceive 3 dimensions ... we see using eyes which see in 2d projections... how ever without even seeing I can figure out there are 3 dimensions.

Of course you do - all our physical senses are built around our existence in three spatial dimensions. This was indicated in an earlier reply. Any creature (assuming it existed) that could percieve more dimensions than us would almost certainly have to either fully or partially exist in more dimensions than us and would therefore probably be either very difficult if not impossible for us to interact with.

Assuming all alien lifeforms exist within the physical universe that we ourselves exist in then they will have senses that are developed to pervcieve those same dimensions that we know and no other ones.

However whether they "see" the universe around them in the same way that we do is very much open to question. Plenty of other animals on earth detect objects in the three spatial dimensions in a wide variety of ways. Some have vision that extends further into the UV end of the spectrum, others further towards the IR end and of course many see either a reduced range of colours or no colours at all. Snakes are known to have a crude thermal imaging system and of course other animals rely on echo location be that in water or air. Furthermore while vertibrates have scanning rotating eyeballs the insects mostly have fixed compound eyes which give them a good alround view of their environment but do not provide the focal precision that vertibrates enjoy.

So there are a wide range of possibilities and each of these opens possiblities and challenges. For example we have needed to develop instruments to allow us to detect radiation that is outside of our visual range. Other species might have to overcome problems that are nothing to us. For example many common skills and crafts carried out by humans rely on our ability to see colour. Metal workers often judge the temperature of the metal that they are working by subtle changes in its colour. An intelligent alien species that could not see colour and which had developed metal working skills would have needed to find another way around this little problem.

One could almost start a whole new thread on the subject as to whether our ability to see as we do was an evolutionary requirement for us being able to develop out technologies. Would an alien species find its own technological development hindered or enhanced if it could not see like us.

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