design language : rules of 5 & 50

Two rules with some very naive science & assumptions based on ‘limited’ user testing experience.

The rule of 5
Based on the classic ‘7 + or – 2’ cognitive science, I suggest that in game design you need to carefully balance the number of active or significant factors a player has to consider as critical to difficulty. A player’s ability to keep decisions, data, key points or themes in their active short term memory varies wildly, but as a rule 5 concurrent things should be considered a reasonable limit. More than this, and the player will more than likely lose track, not make links between things and generally be unable to decode the model or make correlations between things.
Younger kids tend to be able to maintain less concurrent things related to the game, although they may have more concurrent things in their heads at any one time. Experienced gamers, and people who become absorbed in the flow of the game, tend to have more concurrent things.

The rule of 50
Players tend to be able to recall ~50 connections, contacts, facts, locations, names or whatever associated with a subject. e.g. in a MMOG, recognizing 50 avatar names or player contacts is possible, more than this and they become just names or faces.

The two rules work together; you could reasonably expect a player to carry on conversations with ~5 players from a pool of 50, they may switch around which specific players from inside the pool but are unlikely to be active dealing with more than ~5 at any one time.

How many units can you deal with in a strategy game?
How many sub plots or narrative points can you cope with in a story or RPG?
How many moves ahead can you think in chess?
How many people are in your address book, that you can honestly say you currently deal with or recall in detail?
How many bits of data can process to understand the cause and effect model in a build/sim game?

(google use 6 things)

(the magic number)



  1. genecloud said

    Memory principles:
    1. Short term memory is limited to seven plus or minus two chunks of information.
    2. Short term memory is volatile, and users will often forget in the presence of distractions
    3. A schema is a mental model that makes it easier for users to recall an item. Schemas can serve as the basis for “chunks” because the provide a meaningful method for grouping information
    4. Well developed schemata make it easier to remember items that fit within a schema. Thus, experts with well developed schemata outperform novices.

  2. genecloud said

    3 plus or minus 2… helps explain why in usability testing people are good at dealing with 1 thing at a time.
    “Researchers have often debated the maximum amount of items we can store in our conscious mind, in what’s called our working memory, and a new study puts the limit at three or four.”

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