GURPS Powers: Enhanced Senses

[vicky_molokh]

Originally Posted by Fred Brackin

Yes, but your ability seems to belong to such a small percentage of the general population (far, far less than 1%) that amending the rules to cover it looks like a poor use of limited resources.

It might be a useful perspective for modelling how Discriminatory Sense of Smell works, though. Notably, the default flat range penalty seems off. Perhaps Discriminatory Sense of Smell should include one level of long-range smell by default (or '½-level' or whatever), because until P:ES, no animals ever had the range-extension perk!

[Humabout]

Originally Posted by Fred Brackin

Yes, but your ability seems to belong to such a small percentage of the general population (far, far less than 1%) that amending the rules to cover it looks like a poor use of limited resources.

This is actually an excellent application of a perk. Most people cannot do this. Pay a character point to get long range smelling. If you can "see" by smell, that is probably an actual exotic advantage, and should probably be forbidden to humans without an unusual background. Setting assumptions may nullify the need for the UB, but paying points for it remains applicable.

[whswhs]

I think what I have to say about Flyn's part of the discussion is that I really don't understand what he wants. I've suggested a couple of alternate ways to formulate the smell rules; I haven't seen him saying that any of them looks more reasonable. I've discussed the problems with having a systematic set of smell rules like those for sight or hearing; I haven't seen him propose ways to resolve them. I'd like to see him put a proposed amendment to the rules before us, to give us something to debate. I don't think I can really have a useful discussion with what seems to me to be his vague sense of dissatisfaction.

[Anthony]

Originally Posted by whswhs

I tried to base the scales in Enhanced Senses on data rather than anecdotes. Personal sensory experience is just too variable. Unfortunately there don't seem to be good psychometric results for the chemical senses.

However, the physics of how scent travels is decently known (though complex; the math for vision is way easier), the unknown part is mostly what detection thresholds are for various chemicals.

[vicky_molokh]

Originally Posted by Anthony

However, the physics of how scent travels is decently known (though complex; the math for vision is way easier), the unknown part is mostly what detection thresholds are for various chemicals.

Okay, so which range class is the closest playable approximation of the way it travels?

[whswhs]

Originally Posted by Anthony

However, the physics of how scent travels is decently known (though complex; the math for vision is way easier), the unknown part is mostly what detection thresholds are for various chemicals.

Well, that, and we don't necessarily know what concentrations of those chemicals are emitted by what sources.

[Anthony]

Originally Posted by vicky_molokh

Okay, so which range class is the closest playable approximation of the way it travels?

Range/speed chart; animals just have large plusses. There are basically zero real-world situations in which either 'short' or 'long' range is appropriate for senses.

[Bruno]

Originally Posted by Anthony

Range/speed chart; animals just have large plusses. There are basically zero real-world situations in which either 'short' or 'long' range is appropriate for senses.

Even lateral line and electric field sense in fish? I got the distinct impression they were very good close and limited at range, which doesn't match speed-range with a penalty.

[Anthony]

Originally Posted by Bruno

Even lateral line and electric field sense in fish? I got the distinct impression they were very good close and limited at range, which doesn't match speed-range with a penalty.

The basic realistic models are:

• No range modifiers (effects that only propagate along a single dimension, such as vibrations on a string or current in a conductive wire).
• 50% range modifiers (effects that propagate in only two dimensions, such as waves on a surface).
• Simple range/speed chart (light, sound, etc)
• 150% range/speed chart (effects that suffer an inverse cube falloff, such as magnetic or tidal flux detectors). Your field sense examples probably fit here. Scent might fit in here, it depends on whether you've got a single instance or an ongoing source.
• 200% range/speed chart (active sensors beyond effective range -- range both reduces the brightness of the illumination on the target, and the amount of reflected energy coming back to the sensor).
• Any of the above plus linear falloff (the particles involved are absorbed by intervening material, or are unstable and subject to decay); things like vision in hazy conditions, neutron detectors, and the like.

[Bruno]

Aha! OK, division (and multiplication) makes that coherent and consistent.

My intuition is that the electrical field sense would indeed be an inverse cube falloff, but that's based on vague understandings of the physics and what the steriotypical behavior of various animals using it is.

Sharks have lots of sensory pits around the mouth, and rely on detecting muscle activity for last-minute targeting when they're doing the final attack, since they roll their eyes back in their heads to protect them and therefore are blind. This leads to sharks trying to bite fish in nets or on hooks biting at metal boats instead if the fish is e.g. being reeled in.

Platypus bills are covered in electroreceptors too, they use the sense when rummaging around in mud to find worms, and have to shove the bill right into the mud to sense anything. Of course, worms are small targets; no idea what effect the mud has on electroconductivity.

Most fish seem to use lateral-line pressure senses to evade at the last second, rather than at range - but that could be tiny fish brains. It's essentially hearing/touch-vibration sense with a low resolution but high suface-area distributed sensory organ - other than the pressure-sense equivalent of 360 degree vision, I'm not sure how that affects it.