There is an optimum number of steps
Procedures and lists should not have more than X steps; where X is 5, 7, or 9, depending on the variant of the myth.
Hart (Ten Technical Communication Myths) cites Miller’s (1956) study on short-term memory as being the origin of this myth. While Miller’s study on short-term memory is probably valid (for example, it has been cited over 20,000 times), Hart notes that, “several generations of writers have made the assumption that (for example) lists and procedures should contain no more than five to nine steps, based solely so far as I can tell on the title of Miller’s article and the myths that have grown up around it.” Hart describes the nature of Miller’s study, saying that it, “actually discusses the human ability to reliably distinguish categories…(simplistically) how much information your audience can manage at a single time.” Something that might or might be relevant to a printed list of steps. However, Hart concludes his discussion of this point by saying, “our audiences have very real limits on how much information they can process simultaneously, and recognizing the existence of these limits means that we need to better understand how we can help readers to process information.”
Hayhoe (Why We Do the Things We Do) describes how Miller’s observations have been generalized to other applications such as lists and procedures, observing that “No technical communicator who repeats or applies these myths of the field does so knowing that they are myths.”
UX Myths (UX Myths | Myth #23: Choices should always be limited to 7+/-2) includes more references to this notion and quotes from a letter by Miller (original source unavailable) in which he says that his research did not apply to “a person’s capacity to comprehend printed text.” The UX Myths topic also cites Edward Tufte saying “Miller’s paper neither states nor implies rules for the amount of information to be shown in a presentation.”
Pratt (Nine myths about technical writing) says there’s no science behind this [as applied to technical communication applications?] but, takes a pragmatic approach in other myths by encouraging testing to find out for sure.
- Understand the source of the myth and the context of the experiment that serves as its root.
- Understand your audience and how you can write in blocks (chunks) of information that are appropriate to the reader and their goal.
Any rule that includes “always” or “never” (or variants of those concepts) should be suspect. Make sure you’re not generalizing a rule beyond its scope.
Miller, G. A. (1956). The magical number seven, plus or minus two: some limits on our capacity for processing information. Psychological Review, 63(2), 81-97. http://dx.doi.org/10.1037/h0043158