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In the course of designing fictional species I often find myself wishing to use exotic senses which we humans lack. This poses a unique and interesting challenge as without possessing the sense myself I find it very difficult to understand what they can perceive. For the same reasons one can’t describe a color to a blind person or a sound to a deaf person I don’t expect an explanation of what this sense feels like, but rather what it is capable of.

Electrolocation is the ability to detect nearby electrical fields. It is observed primarily in fish as water is much more conductive than air. It comes in two different forms, passive and active.

Fish possessing passive electrolocation are capable of detecting the weak electrical fields that all animals produce by the action of their muscles and nerves.

In active electrolocation, however, fish produce their own electric field which allows them to detect differences in conductance and capacitance in their surroundings.

In order to make the question more answerable let’s focus on active electrolocation. My question is what is an organism possessing this sense actually able to perceive? I'll provide some example questions but don't feel the need to answer them all or limit your answers to them.

  • Can they distinguish between size, distance, and magnitude of distortion?
  • How precise is this directional sense and can it work in all directions?
  • Are there any blind spots to the sense such as the poles of the generated electrical field?
  • What substances would block the sense?
  • Can it penetrate insulating materials?

As further guidelines for what I’m asking for, I’ll give an example. If I were asked to describe the capabilities of our sense of hearing I could say that we can distinguish a wide range of frequencies from each other although frequencies too high or too low are imperceptible to us. We can roughly determine the distance and direction of the source of a sound as long as it isn’t straight in front of or behind us. We have difficulty hearing through insulating materials and we can hear sounds reflected off of other objects which may confuse our sense of direction. I’m asking for an equivalent description of the active electrolocation sense.

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  • $\begingroup$ I don't understand what your question is. You have six bullet points with question marks, but that would surely be too broad... $\endgroup$ – kingledion Sep 11 '18 at 17:57
  • $\begingroup$ @kingledion I'm asking for a general description of how the sense would work. An acceptable answer doesn't need to explicitly answer each of those points nor does it need to limit itself to them. They are just examples of what I am trying to understand. I could split this question into many subquestions but I think answers to each one would overlap and step on each other and so I've chosen to bundle them together. The question is simply what are the perceptual capabilities of active electrolocation? $\endgroup$ – Mike Nichols Sep 11 '18 at 18:03
  • $\begingroup$ I think you should put that first sentence of your comment into the question, in bold, to make sure everyone knows what you are asking. $\endgroup$ – kingledion Sep 11 '18 at 18:05
  • $\begingroup$ Through air or in water? $\endgroup$ – Ash Sep 11 '18 at 18:14
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    $\begingroup$ @Fabby I tend to wait a while before accepting answers to as not to discourage any potential future answers. Forgot about this one though and left it too long. $\endgroup$ – Mike Nichols Jul 2 at 19:11
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Don't think of trying to explain colour to a blind man but a colour to a totally colour-blind alien: a colour is like a black and white shade but more intense so you see the difference better and the same goes for electrolocation:

  • Can they detect the distance of an object?
    Yes, and the closer it comes, the "clearer" the image gets, just like your eyes work.
  • Can they distinguish between, size, distance, and magnitude of distortion?
    Yes, eye analogy again
  • How precise is this directional sense and can it work in all directions?
    The closer, the preciser, all 3 spacial dimensions
  • Are there any blind spots to the sense such as the poles of the generated electrical field?
    Yup, just like the blind spot in one eye: you can have dual electrolocation fields (North-South and East-West) to compensate
  • What substances would block the sense?
    Anything blocking electricity: plastics, wood, ...
  • Can it penetrate insulating materials?
    Erm, no, otherwise they wouldn't be "insulating" but they can look around the tree a bit if it's not too thick as an electric field bends around obstacles.

And most important of all: our senses are not separate but work together as a whole: You can hear a car coming closer, just like you can see it doing the same, smell it after it has passed, and touch it if it gets too close! :-)

So Electrolocation would work in tandem with the other senses the alien has: it would feel the stampeding herd through its foot soles first, hear the herd coming, "feel" the electrolocation changes, ... but don't forget its sense of electrolocation has to be pretty powerful under atmospheric conditions as air doesn't conduct electricity well, but at high enough levels, it does... ;-)

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To take things in order:

  • Can they distinguish between size, distance, and magnitude of distortion?

Not all three without some other data no, a large, low magnitude distortion will appear the same at a certain range as a much smaller but more intense distortion so without independent knowledge of the range to the probable source they can't really tell them apart.

  • How precise is this directional sense and can it work in all directions?

It should be very directionally accurate and depending on the sensor distribution over the creatures bodies it should be accurate in all directions.

  • Are there any blind spots to the sense such as the poles of the generated electrical field?

There is the potential for white-out zones, caused by sensory overload but I wouldn't think there would be dead spots large enough to cause a blanking effect in any natural electromagnetic distortion.

  • What substances would block the sense?

Glass, wood, or an air gap for any but the largest distortions.

  • Can it penetrate insulating materials?

Only when the distortion is large enough to penetrate them.

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  • $\begingroup$ Electric fields don't penetrate isolating materials? Really? Have you never tried to rub a piece of plastic on your hair and attract small pieces of paper through the air? Funny how dirt cheap motion detectors (e.g., those which turn on the lights when a person approaches) work through several meters of air... $\endgroup$ – AlexP Sep 11 '18 at 20:36
  • $\begingroup$ @AlexP Like I said if the distortion is large enough to penetrate "Electromagnetic Distortion" is a really vague term. Huh I thought the cheapo motion sensors used an IR laser. $\endgroup$ – Ash Sep 14 '18 at 15:45
  • $\begingroup$ You have it exactly backwards. Electric fields penetrate dielectrics easily; for example, they go throuh a vacuum unimpended. Electric fields penetrate conductors with difficulty if at all. $\endgroup$ – AlexP Sep 14 '18 at 16:15
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Electrolocation in fishes detects electric fields, normally generated by muscular activity (but also from metals, that's why apparently sharks are sometimes attracted by metallic objects).

My guess is that the fish would sense a stimulus which is as stronger as closer the target is or as intense is the muscular activity.

Depending on the configuration of the organ, it is possible to get a spatial orientation, and the signal would be shielded by any configuration stopping electric fields.

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