[Basic] Advantage of the Week: Acute Senses

[Otaku]

Just because seeing the last few posts reminded me: Basic p.258 explains comprehension rolls, which are against IQ and not Perception and rolled to check against the significance of something you've noticed; you see the rabbit running from the bushes you're investigating, but you need the Comprehension Roll to realize that even though its summer said rabbit has a white winter coat, suggesting it isn't just a wild one.

Perception for a human can be bought up to 20 or lowered down to 4 according to Basic p.16. The bonus from Acute Vision I take it is just representing better-than-normal eyes... but what about people that are just good at Perception with a specific sense? It might be excessive detail, but what about levels of Perception with a "One Sense Only" Limitation (-60%). Yes, priced that way so that its 2 points per level like an Acute Sense; the difference is that it just makes a decent stepping stone for buying up Perception. Probably not needed, but does that look like it would cause problems somehow?

[ErhnamDJ]

Originally Posted by vicky_molokh

People tend to fail to perceive something way earlier than they stop sensing it.

So how do you represent the difference, and how do you make sure people can't sense things outside what is physically possible? How do we mechanically represent the resolution limits of human sight, hearing, smell, proprioception, etc.? Can someone with Perception 15 and Acute Vision 2 see things the human eye can't physically see? What's going on there?

[whswhs]

Originally Posted by Otaku

Just because seeing the last few posts reminded me: Basic p.258 explains comprehension rolls, which are against IQ and not Perception and rolled to check against the significance of something you've noticed; you see the rabbit running from the bushes you're investigating, but you need the Comprehension Roll to realize that even though its summer said rabbit has a white winter coat, suggesting it isn't just a wild one.

Perception for a human can be bought up to 20 or lowered down to 4 according to Basic p.16. The bonus from Acute Vision I take it is just representing better-than-normal eyes... but what about people that are just good at Perception with a specific sense? It might be excessive detail, but what about levels of Perception with a "One Sense Only" Limitation (-60%). Yes, priced that way so that its 2 points per level like an Acute Sense; the difference is that it just makes a decent stepping stone for buying up Perception. Probably not needed, but does that look like it would cause problems somehow?

I look at it a bit differently. To me it seems that Acute Vision is Perception (One Sense Only, Vision, -60%) and is, in effect, a general enhancement of (visual) perception overall.

You really can't do much to boost visual acuity overall past human limits; the human fovea has single neurons as close together as is physically workable for light of visible wavelengths—reduce the diameter and the efficiency falls off catastrophically. Birds of prey do some tricks with ocular geometry, but a lot of what they have is just several levels of Telescopic Vision, which is a change in the physical optics of the lens. Similarly, Night Vision is going to represent changes in the efficiency with which the eye gathers photons, whether because of bigger eyes, wider aperture, or enhanced pooling of retinal responses (or reflective back layers like those in a cat's eyes). Or you could add pigments for UV or near IR or the ability to discriminate which way light is polarized.

This shows up better for the other senses, where for example having more densely innervated tactile receptors is Sensitive Touch, but keener tactile perception is Acute Touch.

Bill Stoddard

[whswhs]

Originally Posted by ErhnamDJ

But the human eye's resolution is limited. The way GURPS represents that is with your Vision sense--whatever that number is. I haven't done the math on it, so I don't know what the limit is, but I don't see how it makes sense to say that a person can "perceive" things at resolutions no human eye can detect. Perceptive ability of the brain isn't what's in question here. If you have two men stand next to each other, and move back away from them, eventually you (and anyone else with a human eye) will no longer be able to discern how many men are there, and that's because of how the eye works, rather than your brain's perceptive ability.

GURPS says that when you are looking for something in plain sight, you get +10 to Perception. But if you look at an eye test, the definition of 20/20 vision works out to 1 minute of arc resolution, which is 0.2 inches at 20 yards or 0.07 inches at 20 feet; that's about -3 for range and -18 for size, for a net -21! Of course you aren't trying to find the eye chart; you already know where it is, and you're trying to see the letters clearly. If you double the bonus for zooming in, to +20, on the model of Telescopic Vision, that gives you a net -1; if you say that Per 11 equals 20/20 vision you're going to have a 50% chance of reading the chart.

Bill Stoddard

[Xplo]

Your vision score reflects your ability to get visual data into your head in such a way that you consciously notice the interesting things, not just the quality of your optics. Someone who notices Sir_Pudding's machinegunner in a bush may have more physically perfect eyes, but more likely he's just more observant: the data analysis software in his head works better.

(Aside: he may also have noticed the machinegunner because he knew to look for it... which could be represented by successful complementary rolls against Tactics or Soldier adding bonuses to vision... which would give players damn good incentive to make sure their characters have those skills! But I leave this, and its variants and implications, as an exercise for the reader.)

Why can you have a guy with IQ 12 and Acute Vision 2, but not a guy with IQ 10 and Acute Vision 4? IMO, you probably could; I would totally buy a fictional character who's not particularly bright but has (metaphorical) eyes like a hawk and spots things that others might not. The limit is more (IMO) to give GMs a guideline as to what's "realistic" for humans so that they're not going "hmm, how much acute vision should my upgraded human template have? 2? 5? I have no idea!" (That it's in Biotech especially makes me think this.) That, and when the guy whose PC already has IQ 15 wants to buy Acute Vision 8, the GM won't feel so arbitrary saying no.

[Otaku]

Glad someone posted the Bio-Tech rule; as I've mentioned I am not actually able to play right now (very slowly getting ready to run a beginner adventure where I am the GM; pity those players) but since I have to do it online and other stuff keeps coming up... like I said, very slowly. So when I've been practicing and building guys, at least for PCs I am used to my old S.O.P. procedure from 3e: unless you absolutely need to squeeze out the points for something else, you just take Acute [Sense]+5 for 10 points for whatever compliments the character most.

So now I'll dial it back, but I still am wondering what Acute Vision is supposed to represent. I assumed it was mostly physiological, hence being required at Character Creation; this is the trait that represents superior eyesight (literally "superior sense" in RAW). Having the cognition/training/etc. to notice things better is Perception, which can be bought after character creation. Oh well, most of my characters seem to favor high PER scores anyway, so I can probably just put the points towards that.

[(E)]

Originally Posted by Xplo

Someone who notices Sir_Pudding's machinegunner in a bush may have more physically perfect eyes, but more likely he's just more observant: the data analysis software in his head works better.

An example of that is Robert Evans an amateur astronomer who found something like 50 supernovae. I can't quiet remember the quote from his mention in Bill Bryson's "a short history of nearly everything" but it was along the lines of "scatter salt over 100 tables, now add one grain and Mr Evans could spot it"

[Eukie]

Originally Posted by ErhnamDJ

So how do you represent the difference, and how do you make sure people can't sense things outside what is physically possible? How do we mechanically represent the resolution limits of human sight, hearing, smell, proprioception, etc.? Can someone with Perception 15 and Acute Vision 2 see things the human eye can't physically see? What's going on there?

The US Armed Forces did a lot of research into this in order to improve their reconnaissance. One result of their research was discovering how much resolution is necessary to do more than just spot something. For example, to be able to spot something, a soldier would need it to span at least three "TV lines", which are equivalent to the resolution; at an acuity of 1.0 (20/20), this is 3 arcminutes. At an acuity of 2.0 (20/10), this is 1.5 arcminutes.

To tell which direction something is pointing in, you need 1.4 times the resolution. To tell what something is in general terms ("that's a person","that's a truck", "that's a tank", etc.), you need 4 times the resolution. To identify it fully ("that's a soldier holding a machine gun", "that's an Ural-4320", "that's a T-72", etc.) you need 6.4 times the resolution.

Using the Speed/Range table, determining orientation is -0, recognizing what kind of thing it is is -2, and identifying it is -3.

[Flyndaran]

There is a skill to perceiving with limited sensory information.
As my visual acuity gets worse, I have adapted to maintain my official corrected vision test results. General poor vision, not just near sightedness.

[Peter Knutsen]

Originally Posted by vicky_molokh

People tend to fail to perceive something way earlier than they stop sensing it.

Yes, that's what makes Sherlock Holme stand out. His ears aren't orders of magnitude keener than the ears of the average person. Nor his eyes, or his nose. But he is almost always aware of everything his senses attempt to convey to his brain, whereas you, and I, and most other people, filter most of that away.