For today’s GURPS-Day and GURPS 101 segment, we continue with the basic stats, this time with IQ and its derived abilities, Perception and Willpower.

Many, if not all, of the comments made about the value of DX are true for IQ. They both have two derived abilities, and both of those are 5 points each. This leaves the skill part of the IQ at roughly 10 per level, giving a boost to 200 skills or so. It’s a ludicrously good deal, and since eleven of fourteen of +Sean Punch‘s list of basic adventuring skills in GURPS have a direct (IQ) or indirect (Per) default to IQ, you can more or less justify as much spending in IQ as you’d like from an “effectiveness” point of view.
How Brilliant Is Required? (IQ)

Since there’s no upper limit on how much IQ you want to buy from a point-effectiveness basis, how much should you buy? Well, I’d probably say that you’ll want to probably approach this from one of two perspectives.

Perspective the First: What seems like a good value? IQ 9-10 is nothing to write home about, and says you’re about average in everything. IQ 11-12 is a steep step up the bell curve, and is high enough to be a defining characteristic. Those guys that are notably brilliant and it’s their defining thing? They’re IQ 13-14 polymaths. IQ 15 and higher will be spectacularly noticeable, and it will be noticable in play. More on that later. Experts in their fields, where that field requires a lot of brain-work, are more likely to be IQ 11-12 with maximum applicable Talent (for effective IQ of 14-16 in those areas, with that added panache thrown in) than raw IQ in that level for plausible and realistic characters.

Perspective the Second: Buy as much of it as you can, from a game-mechanical standpoint, and do it in this order. First, buy as many levels of the appropriate 5- or 10-point Talent as you can. Then buy up your skills to the absolute levels you want. Then “sell back” points in skills, seeing if you can get to enough to eke out boosts to IQ instead. So if you’ve thrown down the requisite 30 points for +3 “Stuff I Want to Be Good At” Talent, and then decided that you really need to be awesome in these seven IQ-based skills (including Per and Will), look at the total points spent in those skills. Got more than 20? Start looking to see if you can have the same skill levels while raising up your base IQ. Munchkiny? Absolutely.

The only issue this raises is one that is fine on paper and annoying as hell in play (at least to me). High-IQ characters tend to be niche-stompers in games with niches. Be warned.

Hey, what’s that? (Per)

I wrote an entire post on Perception last August. I won’t repeat it here. I find Per one of the single most valuable attributes on the character sheet from a “get involved with stuff, and avoid being ganked” perspective. It allows you to hear/see the invisible adversary coming, it allows you to notice those pesky details that avoid the adventure coming to a complete halt, read lips, detect lies, and find cool stuff left over in the garbage heap.

And did I mention not getting jumped?

I have found that Per of 12 seems sufficient, but that probably means Per-14 is even better.

Determination, Grit, and Holy Awesomeness! (Will)

Cadmus has Will-14. It rocks. When dealing with possession, the undead, or if you use The Last Gasp for pushing yourself hard with physical effort, Will is great. I’ve not found a lot of cases where Will-16 through Will-20 is required, but that’s situational. Penalized Will rolls are likely to be a staple of confronting powerful undead creatures, and Contests of Will are common in fiction.

Parting Shot

This is more a matter of “yes, it’s worth the points, always” rather than “is it ever worth it?” IQ (and DX) are the best deals in the game, unless maybe it’s HT, but probably IQ and DX are the winners here. The question is really of point allocation and role. Are you the point man? You want Per, lots of it, and enough of an applicable Talent and skill to push what you want to be good at over the top.

Spellcaster or Cleric? Again, hit up the specific Talents first, then boost Will, then skills, then IQ.

Polymath, good at everything? You annoy me. 🙂 Buy up IQ until the GM and your fellow players throw up their hands in disgust.

Over at the SJG Forums, there’s a fairly involved thread about dealing with attacks from behind.

So, with that:

p. B374: An active defense is a deliberate attempt to avoid a particular attack. It’s only possible if the defender is aware of the possibility of an attack from his assailant and is free to react . . . by moving out of the way of the attack (a dodge), deflecting the attack with a weapon or empty hand (a parry), or interposing a shield (a block).

p. B391: Against an attack that comes from your back hex, you cannot defend at all unless you have Peripheral Vision (which lets you defend at -2) or 360° Vision (which lets you defend at no penalty).

p. B391 – Runaround Attacks:  A fast-moving fighter can sometimes start in front of a foe and run behind him to strike from his back hex. Against a true attack from behind, no active defense is possible, because the victim did not know the attack was coming. If the attacker starts in front and runs behind, outmaneuvering his victim through sheer speed, the victim does know he’s being attacked.

Technical Grappling, p. 11 – Rear Arc:  When grappled, you know where your foe is! You defend against his attacks from your rear arc at -2 (as if from the side) if standing, crouching, or kneeling, or at -4 otherwise.

 To me, it’s going to be pretty simple. If your cannot perceive the attack in any way, you may not defend.

In my article Dodge This, from Pyramid #3/57, I spent some time on the Vision part of Perception rolls. I didn’t spend that much time – only a throwaway line – on other senses. Still, one big one is going to be hearing, as many people and critters will growl or give off some warning when they attack. Hearing is more of a 360-degree sense, and if you make a Hearing-2 roll against an invisible foe, you may parry or block at -4 . . . at least from the front. You may dodge at -4 if you’re aware you’re being attacked (again, this doesn’t specify arc, but I’ll assume mostly from the front). This is all covered on p. B394.

The way I read the rules, especially the quickie table on p. B549, is as follows

1. If an attack is from behind (excepting runaround attacks and pre-existing grapples), you don’t get to defend.

2. If an attack is not from behind, you may only defend if you can succeed in some sort of Perception check. Penalties for Vision rolls are given in various places, and Hearing at -2 is a good option even against invisible foes. You still get plugged in the back if the attack starts there, though.


There are always exceptions, and one I might make would be that if you’re being attacked from behind, you might be able to make a Hearing-based Melee or Unarmed Combat Skill roll, penalized, to hear your foe’s footsteps, breath, rustle of clothing or jingle of mail.

The only defense you can make is a Dodge, and you must either Retreat by stepping away from your foe, or if you feel compelled to stay in your own hex, Change Posture to kneeling or lower.

For penalties, I’d make it -2 generically for ‘can’t see attacker,’ -4 if you’re wearing a helmet that covers the ears, -4 if you’re actively fighting someone else, and likely another -4 for rear, rather than side or front arc.

That’s basically Hearing-6 if you’re just standing around, Hearing-10 if you’ve got open ears but are fighting someone in front of you, or have Hard of Hearing because you’ve got a helm on your ears, or a whopping Hearing-14 if all apply. If your Hearing roll drops below 3, you can’t rolll.

Parting Shot

The simple rule, attacks from the rear hex get no defense, is what we use in +Nathan Joy‘s DF game. It’s accepted by all, and we use it to our own advantage as much as the bad guys use it to theirs. The easiest way to deal with a foe in your rear hex is to either (a) have friends who can watch out for your, or (b) turn a bit to expose your peripheral vision to various arcs. But by and large, the reason you just get nailed if an attack comes from your rear hex is that it works in play. 

Observation gets a lot of confusion and hate on the boards due to some fluff text in the beginning. Still, what’s going on with Perception and other perception-based skills? When should each be used?


As far as I can tell, this one is simply sensory acuity, with a small side-order of data processing. One can make a pretty good argument that any Vision roll higher than 12 for humans is processing, rather than native resolution, which turns this on its head and suggests that while the first 10 points in Per is sensory acuity, anything beyond that is interpretive skill. That would make +2 Per a legit thing from a purely “my equipment is better,” but after that, a GM would be within his rights to treat further levels as a Talent, at 10 points/level, maximum 4 levels!

That last point isn’t a recommendation or a “do it this way!” or complaint about the price of Perception. I’ve not seen it break any games or even cause WTF moments. It’s just that for realistic/biomechanically accurate humans, there are actual hard limits that seem to correspond well to about two levels of natural ability, and then beyond that, the “wow, this guy’s really good at this” factor kicks in from processing and interpretation, which seems really a lot like the Reaction bonuses Talent gives you.

Per-based Skills

So, checking out the skills list, which skills are based off of Perception? What is the primary purpose of each skill?

  • Blind Fighting (Per/VH): Allows one roll per turn to be able to make an attack or defense in darkness.
  • Body Language (Per/A): Can use it like Empathy (p. B51) or Detect Lies (p. B187).
  • Detect Lies (Per/H): Gives a yes/no on whether the subject is lying to you.
  • Esoteric Medicine (Per/H): Somewhere between First Aid and super-healing. Interesting that this is a Per skill, but Diagnosis is not. 
  • Fishing (Per/E): Ability to catch fish.
  • Lip Reading (Per/A): See what others are saying within 7 yards.
  • Observation (Per/A): Obtain details that are tactically significant when contemplating dangerous or “interesting” action. May require another roll to put it all together.
  • Scrounging (Per/E): Find, salvage, or improvise needed equipment.
  • Search (Per/A): The ability to perform a hands-on or electronically assisted search for items concealed on a person, vehicle, bag, etc.
  • Survival (Per/A): The Per-based utility of this skill is to find water, food, shelter, and avoid hazards. Best direction to travel to find (or avoid) particular terrain features.
  • Tracking (Per/A): Follow a man or animal by its tracks
  • Urban Survival (Per/A): The physical part of staying alive in a city. Find (rain)water, manholes, building exits and entrances, find a warm place to sleep, and a host of other things.

Per-default Skills
Fishing (Mythos) (Per/VH)

As opposed to those with Per as a base, which skills can also default from Perception. These are ordered by difficulty of the defaults.

Easy Skills
Fishing (Per-4)
Scrounging (Per-4)

Average Skills
Observation (Per-5)
Search (Per-5)
Survival (Per-5)
Tracking (Per-5)

Some furies are blinder than others

Hard Skills
Detect Lies (Per-6)
Esoteric Medicine (Per-6)

Average Skill with Strangely Huge Default Penalty
Lip Reading (Per-10)

No-default (you can’t use them without training)
Blind Fighting (Per/VH) – no default.
Body Language (Per/A) – defaults to other trained skills, not Perception.

Type of Skill

Looking at this same list, what is it that is in common with each Perception skill? Let’s break ’em down, but I’m definitely pre-judging my description here to make a point.

  • Blind Fighting (Per/VH): Interpretation of sensory inputs to give a location of a foe, as well as whether he’s attacking you.
  • Body Language (Per/A): Interpretation of sensory cues to determine whether subject is intentionally giving false information or acting in a way known to be out of character for him.
  • Detect Lies (Per/H): Interpretation of sensory cues to determine whether subject is intentionally giving false information.
  • Esoteric Medicine (Per/H): Interpretation of physiological and semi-mystical cues to heal. Plus actually healing someone.
  • Fishing (Per/E): Interpretation of environmental cues to locate the best place where fish are. Also the act of physically catching fish, knowing what lures/bait to use, etc.
  • Lip Reading (Per/A): Interpretation of physiological speech patterns to determine spoken message without hearing it.
  • Observation (Per/A): Interpretation of visual information, but with a very particular slant – that of understanding how to approach safely or stealthily, plus a notion of the tactical situation. 
  • Scrounging (Per/E): Knowing where to look for something, what can be usefully substituted, and getting it, if it can be gotten without undue effort.
  • Search (Per/A): Interpreting visual and touch-based clues to determine if someone’s hiding something. Also performing the actual search.
  • Survival (Per/A): Interpreting the local environmental cues to find basic necessities. Plus a strong side-order of knowing what to look for and how to get it.
  • Tracking (Per/A): Knowing how to interpret disturbances in the environment in order to track a man or beast.
  • Urban Survival (Per/A): Interpretation of location and environmental information in a city to ensure access to food, water, shelter, and safety.

The text that is not in italics seems to basically be “interpretation of sensory data” to me. The italicised text is notable for having non-informational content to it. Fishing being Per-based would suggest “hey, that’s a great place to catch fish,” but it also seems to let you do it (which might be DX-based), as well as know how (which sounds IQ-based). Search has a fairly strong IQ and DX component to it, and Esoteric Medicine lets you do a lot based on Perception, since it’s at least as good as First Aid, and could be a lot better, depending on the campaign.

When To Use Each One?

In short, I suspect that defaulting to Perception rolls to do more than see, hear, or smell something is giving too much credit to what seems to be an ability based on detection, not analysis or interpretation. Generically, if you want to munge detection and analysis into one roll, you’ll want to consider the odds of first detecting what you want to do, and then successfully interpreting it. Based on the defaults above, that’s a Per roll, followed by something that’s going to feel like Per-5.

Can you do that simply? 

Absolutely. If you want to make an instant (one-second) check in combat time to detect and interpret something that you are skilled in, simply roll vs. Per-6 to get that done. If you can take 30 seconds to look, then you may roll vs. Per-2 instead.

Both of these numbers are based on the odds of making a Per roll, then a Per-5 roll, and converting that backwards to a single penalty.

If you have the relevant interpretation skill at Per+1 or Per+2, you may roll for a one-second “detect and interpret” at a -1 penalty to skill, and if you have the interpretation skill at Per+3 or higher, you can always roll raw skill to detect and interpret.

That will give you an informed but cursory impression, and taking extra time can be used to give a higher margin of success.

Parting Shot

In general, and especially in combat, rolls to get actionable information, as opposed to “I see an orc” should always be based on a skill, rather than raw Perception. In fact, I’d probably want to really start to limit the use of raw Per to give anything but yes/no answers, and require some significant margin of success on a roll to get game-useful detail.


Finally, Observation gets a lot of crap on the boards due to a lead-in sentence that could probably use some killin’. Here’s what it says:

This is the talent of observing dangerous or “interesting” situations without letting others know that  you are watching.

and here’s what it really means/should say:

This is the talent of observing dangerous or “interesting” situations.

If you can get over any interpretation based on the “letting others know that you are watching” thing, then your life as a player or GM will be much easier. In short, Observation is the skill of knowing what to look for in a tactical way about clusters of people, or architecture/landscape. What to do about it may be Tactics or Intelligence analysis. Observation lets you collect facts.

What facts? I’d hazard (but not limit) someone with Observation can tell by looking:

  • The militarily relevant count of a group of people (platoon strength, battalion strength)
  • The nature and pace of sentries
  • Good spots for security systems or traps, including minefields; a yes/no might not be available on their actual presence, but good places to put them will be revealed
  • Potential approach avenues for assaults or sneaky movement

To do this without being seen, you will need to make use of Stealth and Camouflage, and cannot just rely on a good Observation check. Or Acting. The one exception is if you’re using Observation to check out a person more or less in plain sight, I would not (on a success) have the svelte bodyguard come up and give you a beatdown for eyeballing her. You’d get that info “without letter her know you are watching.”

I’m nearly positive that bit of fluff text is there for that reason, and not to have Observation somehow act as a proxy for Stealth and/or Camouflage.

A lot of the recent article Dodge This was focused on Perception rolls, specifically and most often, Vision rolls.

In GURPS, if the thing you’re looking at is “in plain sight,” then you get a +10 bonus to Vision to see it.

Not in plain sight?

That’s a big bonus . . . sort of. +10 is basically “you can see it fifty times more easily than in a more obstructed field of view.”

Or, another way, you can see a man-sized target as clearly at 100 yards “in plain sight” as you can see at a six-foot distance in somewhat more challenging conditions. More or less “you can see someone at the other end of a football field as easily as you can at the tip of your spear.”

But what does “in plain sight mean?” Can you ever not be in plain sight?

I was thinking about this in two ways. The first was somewhat mechanical (shocked, shocked, I know you all are). Basically, if the line of sight from you to your target, and 10x farther than that is basically unobstructed, he’s in plain sight.

So if you’ve got a quarry 50 yards out, then (to first order), if there’s basically nothing in the way from you to 500 yards in the direction of your target, he’s in plain sight and you can claim that bonus.

Why? Well, I figure that there are two parts to it. One is a line from you to him, but the other is “what’s behind him that might obscure or confuse the viewer?” If the nearest terrain is 10x farther away than the object is, well, that’s probably OK.

That’s probably a sub-optimal solution, though. Math for no gain, etc.

What I’m thinking is the better solution is that when making a Vision roll, just roll vs Vision+10 in all circumstances. Objects are, by default, treated as being “in plain sight.”

Then you can just apply the usual penalties for range (which are darn steep, -10 at 100yds, and -18 at a mile), purposeful and natural camouflage, stealth, and lighting.

Abrams and T-72 (I think)

Note that the “can you see it at one mile” thing isn’t necessarily a bad joke. An M1A2 Abrams tank is about SM+4 or SM+5 (probably +5, since the T-72 is +4 in High-Tech). It can certainly kill you deader than hell at that range without trying that hard. For a normal guy on an open field, that’s Vision+10, +5 for size modifier, and -18 for range. Net of Vision-7, or about one chance in six of spotting it. Camouflage or poor light makes it even less likely. You’re dead before you know he’s even there.

Not that I’m saying it’s unrealistic. It’s probably about right.

But it seems to me that the “in plain sight” modifier is best handled by just giving it all the time.