Friday, October 21, 2011

Roll Versus Perception - Thoughts On A New Ability Score

"Release me! I've told you everything I know!" the captive pigman spat. Goldar considered the bound creature's words before leaning forward with a sneer. "You're lying," he said matter-of-factly. "You stink of deception."


As they entered the warehouse, Snaxix held his hand up, motioning for the group behind him to stop. As they stood in silence, he swept his eyes across the open area. "We're being watched," Snaxix said. "I think we're walking right into an ambush."


"Where'd he go?" Dr. Faustion asked as he glanced around the library. "I though we saw him dart into here!" Cygus-14 clanked over to a rug on the wooden floor. Reaching down, she pulled it away, revealing a hidden trapdoor. "Open sesame," the cyborg stated with just a touch of humor.


It's a situation that often surfaces in your games -- An NPC is telling a bold-face lie. An enemy lies in wait for the PCs. An important MacGuffin is hidden from the party. In each case, it is important for the party to deduce the nature of the deception, but how do you role-play these events? Well, I've seen this handled in a few ways:

AD&D - My DM had two methods: If it was a "find the hidden thing" roll, he'd have us roll the standard "Detect Secret Doors" check (1 out of 6). If it was a "detect the lie/make a leap of deductive logic," it'd be a check versus Wisdom (d20 versus your ability score). So either you had a straight 16% chance of finding a hidden thing (crazy low chance) or, with an 18 WIS, you had a 90% chance of catching someone in a lie/detecting an ambush (crazy high chance). Both of these seemed wildly out of balance.

Villains and Vigilantes - This superhero RPG was unusual in that it had a specific check specifically for these events. There is both a "Detect Hidden" and "Detect Danger" score given to each PC based upon his INT score. Higher the ability score, the higher the percent chance for your "Spidey Sense" to kick in. It was elegant, although it seemed like it skewed low. With an 18 INT, a PC had a 14% chance to Detect Hidden and an 18% chance to Detect Danger. A hero had to have some kind of super-mega-ultra senses to keep from stumbling around oblivious to dangerous situations or to find anything that's been concealed.

Mutant Future - Many Mutant Lords I've encountered use a roll versus a PC's Intelligence score to notice something amiss or to discover something hidden. But I always thought of INT as a measure of how smart the character is, not how observant the character is. Smart people aren't necessarily the most observant. There is no "Wisdom" equivalent to work with in Mutant Future, as Willpower is in play now. And that is a measure of a PC's internal fortitude and mental strength. So we're a bit stuck...

As you can see, I've given this a LOT of thought.

Mutant Future really doesn't have a system in place to role-play these "flashes of intuition." So I've endeavored to try to work out something to simulate those sudden moments of intellectual clarity. As I see it, everyone's ability to notice minutiae is different. Some are more observant than others. Also, some folks have a more intuned "sixth sense" when it comes to intuition. They pay attention to that prickly feeling on the back of their necks when something is wrong. To reflect this, I offer a new PC ability score -- the attribute we'll call "Perception." This score -- unique to each PC -- comes into play when the PC has a chance to intuitively notice when something is amiss, or when he and the party are in great danger.

*** Perception As An Ability ***
Just as a character's physical and mental prowess are given ability scores (STR, DEX, INT, CON, WIL, CHA), a PC's Perception (PER) should also be graded. When a PC is first generated, he should also roll for his PER using the same 3d6 method as his other scores. Once generated, refer to the Perception Ability Table to determine the PC's Insight % score and To Hit/Damage modifier:

PER --- Insight % --- To hit/damage modifier
3 --- 5% --- 0
4-5 --- 9% --- 0
6-8 --- 12% --- 0
9-12 --- 15% --- 0
13-15 --- 18% --- +1
16-17 --- 21% --- +1
18 --- 25% --- +2
19 --- 28% --- +2
20 --- 30% --- +2
21 --- 33% --- +3

Any time a PC is trying to locate a concealed item or enemy, or if immediate danger is in the area, the ML should call for a roll versus his Insight % score. Average scores (9-12) reflect percentage chance that's close to the 1 in 6 Secret Doors detection chance. Using that as a base, those PCs higher than average are more observant, and thus have a higher Insight %. And, conversely, lower PER scores equal a lower Insight %.

Standard Perception checks on a d20 can be made for fairly obvious observations. ("Which of these mutants is the tribal leader?" (PER roll) You're fairly sure it's the guy with the top hat everyone is gathered around.") I would also use a standard PER check if the PC is trying to recall a bit of information. ("Which direction did the trader say to go? (PER roll) "You remember that he said to go west, staying on the trails.")

In my opinion, a character with a high PER is probably very observant during combat. He intuitively knows a foe's weaknesses, giving him a slight advantage during combat. This is reflected in the To Hit/Damage bonus for high PER scores. However, there is no combat penalty for lower PER scores, as the PC just doesn't pick up on those subtle "tells" in a fight.

To wrap up my thoughts on this, the ML is encouraged to adjust the PER score of any PC who has a mutation giving them enhanced senses. To keep things simple, any mutation that enhances any of a PC's physical senses should be reflected in a +1 to his PER score. Certain mental mutations could also increase this score as well at the ML's discretion. (This is why the table goes up to 21, although I suggest that this score is the uppermost limits of perceptive ability.)


NEW MATERIAL BEGINS HERE: I had it pointed out to me that an article appearing in Dragon Magazine Issue 133 discussed a similar concept. I found the article mentioned and -- I'll be damned -- "Notice Anything Different? The Perception Score: A New Way of Looking at Things." Nearly identical to my post too. So, here's another idea:

*** Perception As An All-Encompassing Average ***
A character's ability to "sense" the unseen could be said to encompass all of his senses. What he sees, hears, smells, and feels all contribute to his perception of the world around him. Therefore, a person's Perception as an all-encompassing heightened ability could be said to derive from all of his other abilities, ie, his Strength, Dexterity, Constitution, Willpower, Intelligence, and Charisma.

To reflect this, the PC should calculate an average of all of his scores (rounded up), then multiply it by 1.5 for his final Insight % score. So:
STR -14
DEX -12
WIL -12
DEX -9
CON -17
+ CHA -16
TOTAL = 80
80/6 = 13.333 = 14
14 x 1.5 = 21% Insight score

Rather than a new ability score, this quick calculation will give each PC his individual Insight percentage chance. Not as cumbersome as a new ability score, and the better a PC is at everything else, the better his chances of being in touch with the world around him.


The band of nomads walked nervously along the bottom of the canyon. Suddenly, the scout riding at the front of the caravan sat up in his mount's saddle. He brought his blaster pistol up and, without a word, fired a shot into a nearby tree. A hidden sniper tumbled from the upper branches and hit the ground with a thud. Still silent, the scout re-holstered his gun and motioned for the caravan to keep up with him.


  1. There was an article on Perceptions in Dragon #133 which we used for a while after it came out. I thought it was one of the better supplemental rules from the magazine.

  2. I had no idea. I'll check it out. Thanks for the tip!

  3. I've used Int, Wis & Dex averaged for the Perception score, for years. A friend turned me on to that method and I'm wondering if it originally came from the Dragon mag Stuart mentioned.

  4. I'm loathe to add new stats (I'm lazy like that), but your system could work.

    Here's an idea. Howsabout just doubling the INT (or WIL) score, and then rolling that number or less on d100? It both skews slightly higher than 1 in 6, and gives slightly better odds at the higher ends.

  5. On Stuart's recommendation, I located and read the article he discusses. I'll be damned if my "original idea" wasn't nearly identical to the Dragon 133 article.

    Well, I stand by my assertion that I came up with this system on my own and didn't crib anything. Even if I was beaten to the punch by 23 years. ;)

  6. OK, I pitched an alternative system I had mulled over and added it to today's blog post. The alternative method steers clear of a new ability score and is instead based upon all of a character's ability scores. Check it out and give me your thoughts.

  7. Elegant and painless. I approve wholeheartily.

    Consider it yoinked for my game.