Seven, Plus Or Minus Two
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Basic Information

The human mind can evaluate (and store in short term memory) between 5 and 9 parcels of information at a time. More than that leads to analysis paralysis (or just forgetfulness). If you're asked to evaluate more than 9 things at once, you're likely to make a mistake, or find the effort fatiguing. This is a generalization, and it varies a bit from person to person, and also depending on what type of task you're attempting. But as a general rule, when you start pushing options beyond 7, things get hairy.

And of course, groups are subject to the lowest common denominator, so "7, plus or minus 2" might be better read as "5, maybe 6 if it's easy." This is especially true when you're putting something up for a vote, or expecting a person to follow up on something without guidance.

See Also:


2. Delta's D&D Hotspot - gaming blog
3. Emerald City Game Fest - gaming blog (the article linked is more about experience, but discusses Seven +/- 2 concept in a section on Levels vs Point-Buy)

Game and Story Use

  • This argues heavily for simplification in character creation, especially for new players, or when gaming with people you don't know very well.
    • Point-buy systems and similar open-ended mechanics can result in plenty of overlooked items, like the cop character who lacks skills he would have needed to graduate from the academy. "I got Firearms, Streetwise and Investigation, but I forgot Driving."
      • This came up recently in my Deadlands game, halfway through the first session the veteran Texas Ranger PC realized he didn't have Notice, and walked right into an ambush.
    • Proliferation of character classes can have similar problems as well. If you've got a dozen variants on Fighter, it becomes pretty tricky picking the most effective one.
    • Lack of Transparency aids the Munchkin in their quest to cheat, or just weasel up the abusive power combos. The more complicated it is, the easier to hide cheat. Also, the more complicated it is, the more likely that other players will undervalue options and powers that the munchkin can use to dominate the game.
      • Simple decision trees allow the casual gamer, narrativist, and method actor roleplayer types to remain competitive with the munchkin without resorting to min-maxing themselves.
        • The sad, somewhat ironic truth of this is that the method-actor types often chafe at the way character class system confines them and prevents them from making a unique character. I know I do.
  • The concept applies to die rolls and combat systems as well.
    • Once you get past 9 possible modifiers to die roll (especially if most rarely come up), someone's gonna forget a bonus or penalty somewhere.
      • It sucks to finish a fight, losing a character's life in the process, and then remember later that there was some situational bonus you'd forgotten to include that would have saved them.
    • Likewise when there's half a dozen different status effects in play, and different timers on each of them.
    • A character with more than 9 different attacks or combat maneuvers starts to get cumbersome. It's less of a problem if some of them are single-use powers, and can be marked off as you consume them, but even then your first fight of the session risks being overwhelming.
    • A GM trying to run 9 different NPCs or monsters will have trouble as well.
      • One solution is to use mook squads rules (like in Cartoon Action Hour or 7th Sea RPG) to abstract groups into a single roll or action
      • A less mechanical option is just numbering them and going down the list every round. But again, while numbering keeps you from forgetting someone, it doesn't make it any easier to juggle all the combat options at once.
  • More than 6 or 7 suspects will boggle the mind, and shut down a mystery scenario. Too many suspects is more effective in slowing a scenario down than having too few suspects - and it has the advantage of being a tiny bit less frustrating or boring, 'cause there's always another suspect to lean on.
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