what is seven plus minus two rule for information design?  

The rapid pace at which the Web has evolved has placed an incredible strain on those faced with the task of creating web sites. It is only natural, then, for web site creators to grasp onto anything posing as standard to accelerate their own work. But many so-called standards have little justification to warrant their continued use. As we move into what some refer to as the 2nd-generation web, it is fitting to reexamine current web practices.

One guideline that needs closer attention is the "Magic Seven, Plus or Minus Two" (7±2) rule of thumb. This principle has often been applied to determine the number of items in a navigation menu on a web page. It arose to satisfy a tactical need to make quick design choices and to objectively justify navigation to site stakeholders.

But where did this rule come from?

Psychologist George Miller published the original study in 1956. Since then, the (7±2) rule has been cited frequently by interface designers. A closer reading shows that Miller makes no conclusions that can be directly applied to web navigation.

First, Miller was studying the limitations of short-term memory. He concluded that there is a limit to the amount of items the immediate memory can retain: (7±2). He wasn't studying how many items humans can perceive, which he admits can be thousands. Web site navigation, however, is generally not concerned with short-term memory. Visitors are rarely required to memorize items in a menu. In fact, many site navigations are presented on all pages at all times for continuous reference. Immediate memory doesn't play a significant role.

Second, it is astounding that this outdated study has survived so long. While Miller's research was well executed, it is simply not current enough to be applied to web design. More recent studies have shown Miller's conclusion to be inaccurate and oversimplified. Also, in the 50 years since Miller's study, our ability and willingness to sift through information has probably increased, particularly with the rise of the Internet.

While Miller's "Magic (7±2)" principle reminds us of moderation, it is not appropriate for fundamental navigation decisions and leads to an arbitrary "one-size-fits-all" solution. In no event should it be taken as an absolute law. On the other hand, spamming site visitors with hundreds of navigation links is also irresponsible. Feelings of confusion and information overload are problematic. There probably are limits to the number of menu items a web page can display without overwhelming the user, but these do not come from Miller.

Clearly, the optimal number of menu items cannot be reduced to one generalized rule applicable in all situations. Instead, when planning the information architecture of a site, the two most important considerations are breadth versus depth and the display of information.
Breadth vs. Depth

Breadth vs. depth refers to the balance between the number of visible menu items on a page (breadth) and the number of hierarchical levels in an information structure (depth). There is a clear tradeoff: The fewer the navigation items at a time, the deeper the structure; conversely, more navigation items at once results in a broader structure with fewer levels of hierarchy.

Research strongly shows that broader structures perform more successfully than deeper structures in general. Users are better able to navigate and find information in shallow hierarchies. Indeed, the most popular sites on the Web today often have broad structures: It is not uncommon for successful portals and news sites to have 50-100 links (or more) on the homepage.

Here's the theory: The effort it takes to repeatedly choose categories across many levels of a deep hierarchy outweighs the effort to scan many items in a broad navigation.

Users also have a greater chance of getting lost in deeper structure

Answered by shepherd at 6:16 PM on April 17, 2008

The seven plus minus rule has often been applied to determine the number of items in a navigation menu on a web page. It arose to satisfy a tactical need to make quick design choices and to objectively justify navigation to site stakeholders.

Answered by Kamlesh B at 4:40 PM on April 17, 2008

One guideline that needs closer attention is the "Magic Seven, Plus or Minus Two" (7±2) rule of thumb. This principle has often been applied to determine the number of items in a navigation menu on a web page. It arose to satisfy a tactical need to make quick design choices and to objectively justify navigation to site stakeholders.

But where did this rule come from?

Psychologist George Miller published the original study in 1956. Since then, the (7±2) rule has been cited frequently by interface designers. A closer reading shows that Miller makes no conclusions that can be directly applied to web navigation.

First, Miller was studying the limitations of short-term memory. He concluded that there is a limit to the amount of items the immediate memory can retain: (7±2). He wasn't studying how many items humans can perceive, which he admits can be thousands. Web site navigation, however, is generally not concerned with short-term memory. Visitors are rarely required to memorize items in a menu. In fact, many site navigations are presented on all pages at all times for continuous reference. Immediate memory doesn't play a significant role.

Second, it is astounding that this outdated study has survived so long. While Miller's research was well executed, it is simply not current enough to be applied to web design. More recent studies have shown Miller's conclusion to be inaccurate and oversimplified. Also, in the 50 years since Miller's study, our ability and willingness to sift through information has probably increased, particularly with the rise of the Internet.

While Miller's "Magic (7±2)" principle reminds us of moderation, it is not appropriate for fundamental navigation decisions and leads to an arbitrary "one-size-fits-all" solution. In no event should it be taken as an absolute law. On the other hand, spamming site visitors with hundreds of navigation links is also irresponsible. Feelings of confusion and information overload are problematic. There probably are limits to the number of menu items a web page can display without overwhelming the user, but these do not come from Miller.

Clearly, the optimal number of menu items cannot be reduced to one generalized rule applicable in all situations. Instead, when planning the information architecture of a site, the two most important considerations are breadth versus depth and the display of information.

Answered by keshto at 11:32 PM on April 16, 2008

Well Sudharsan , "The Magical Number Seven, Plus or Minus Two: Some Limits on Our Capacity for Processing Information" is a 1956 paper by the cognitive psychologist George A. Miller.

In it Miller showed a number of remarkable coincidences between the channel capacity of a number of human cognitive and perceptual tasks. In each case, the effective channel capacity is equivalent to between 5 and 9 equally-weighted error-less choices: on average, about 2.5 bits of information.

Miller did not draw any firm conclusions, simply hypothesizing that the recurring sevens might represent something deep and profound or be just a pernicious, Pythagorean coincidence.

Working memory is generally considered to have limited capacity. The earliest quantification of the capacity limit associated with short-term memory was the magical number seven introduced by Miller (1956).

He noticed that the memory span of young adults was around seven elements, called 'chunks,' regardless of whether the elements were digits, letters, words, or other units.

Later research revealed that memory span does depend on the category of chunks used (e.g., span is around seven for digits, around six for letters, and around five for words), and even on features of the chunks within a category.


The concept of a limit is illustrated by imagining the patterns on the faces of a die. It is easy for many people to visualize each of the six faces. Now imagine seven dots, eight dots, nine dots, ten dots, and so on.

At some point it becomes impossible to visualize the dots as a single pattern (a process known as subitizing), and one thinks of, say, eight as two groups of four. The upper limit of one's visualization of a number represented as dots is the subitizing limit for that exercise.

The film Rain Man, starring Dustin Hoffman, portrayed an autistic savant, who was able to visualize the number represented by an entire box of toothpicks spilled on the floor.

For more details , Please visit the source site :

http://en.wikipedia.org/w iki/The_Magical_Number_Seven,_ Plus_or_Minus_Two

Answered by Alok Gupta at 10:48 PM on April 16, 2008