We all know there are critters on this Earth with senses far beyond (or, at least, different from) those of mortal man... but how often does anyone think about what this actually means for those creatures? One's senses are the portal through which one experiences the world around oneself, and that experience can't help but be colored by the nature of one's senses. If you want evidence for this assertion, you need look no further than the last sentence -- the word "colored", in specific. Does anyone doubt that this kind of optical metaphor could only occur in the language of a species which is strongly dependent on the sense of vision? In fact, we humans are so visually oriented that we use visual references even when describing unrelated, non-visual, sensory impulses! Musicians speak of "bright" and "dark" tones (hearing); temperature can be "white"-hot (touch); and so on, and so forth.

How would the human mind be different if human senses were different? To answer this question, let's take a look at those senses -- how they work and why.

For the most part, the intrinsic characteristics of vision are those of light itself. First, it's a long-range sense; unless they're physically blocked, photons can be detected across a literally astronomical distance (see also: the night sky). Second, it's highly directional -- photons travel in straight lines, barring transit through prisms and such. Third, it's a very high-bandwidth sense, i.e. it's one which carries a lot of information. Fourth, it's a very immediate sense; the moment the light stops shining is the moment vision craps out on you.

Hearing is quite different from vision, and the root of the difference is the underlying physical properties of sonic vibrations, as compares to those of photons. Hearing is a long-range sense, yes, but far less much so than vision -- and one which is far less hindered by intervening obstacles, since sound waves can easily be carried by the atoms and molecules of substances that are opaque to light. Since sound waves radiate out from their source in ever-expanding circles, hearing is distinctly less directional than vision. As well, audible sound waves having a much lower frequency than visible light, hearing cannot carry as much data as vision. And finally, hearing offers somewhat more of a window to the past than does vision, since sound waves do take longer to dissipate than light waves.

The sense of smell, which is essentially high-end chemical analysis of airborne molecules, is very short-range -- the farther the source of those molecules, the more they disperse in air, until their concentration falls below the point where the human nose can sense them. This sense is only marginally directional, if even that. It can tell you how close you are to a thing, and depending on what sort of scent-traces you have to work with, you might be able to tell what direction the trace-leaver was moving when it left its traces. It's not clear how much information can be carried by odors; we humans don't really use our noses all that much, and no species which does, has enough of a vocabulary to clue us in on what we're missing. And since odors can linger detectably for weeks or even months, it's clear that the sense of smell can tell us quite a bit about the recent past.

Touch is definitely not long-ranged. Indeed, were it not for the fact that tactile sensations can tell us about local air currents, hence about moving objects in the near vicinity, it would be perfectly accurate to say that touch is a non-ranged sense! Air currents aside, touch is non-directional -- you may know which part of your body was tapped by something, but can you tell from which direction that tap came? The bandwidth of touch isn't clear, but the size of the bumps used in Braille writing suggests that it's fairly low. Finally, touch is a very immediate sense; the moment a given tactile stimulus goes away, the corresponding sensation vanishes with it.

Taste, like smell, is all about chemical analysis. But whereas smell focuses on those molecules that are volatile enough to diffuse into clear air on the way to your nose, taste is about molecules that your tongue must be brought into physical contact with. Thus, taste has no range, nor is it directional. The information-carrying capacity of taste is likely to be similar to that of smell, and taste may offer as much of a window to past events as smell does.

When writing about a critter whose senses are different from those of humans, consider how those differences might affect your creature. If it depends as much on smell as humans do on sight, the recent past will 'speak' to it constantly, which is likely to affect its concept of the passage of Time. Vision-bound humans have a highly precise sense of Space, of Location; a smell-bound sentient creature might not be concerned with specific points but, instead, be more focused on the relationships, both spatial (i.e. Near and Far) and temporal (i.e. Soon After and Long Before), between those points. And while you're at it, you might want to also consider how your critter acquired the particular senses it has, what sort of environment it evolved in; what kind of selective pressures would result a creature which is as focused on the sense of taste, say, as we humans are on vision?