Progressive disclosure is an interaction design technique often used in human computer interaction to help maintain the focus of a user's attention by reducing clutter, confusion, and cognitive workload. This improves usability by presenting only the minimum data required for the task at hand. The principle is used in journalism's inverted pyramid style, learning's spiral approach, and the game twenty questions.
Contents
Definition and term use
Progressive disclosure is an interaction design technique that sequences information and actions across several screens in order to reduce feelings of being overwhelmed for the user. By disclosing information progressively, you reveal only the essentials and help the user manage the complexity of feature-rich sites or applications. Progressive disclosure follows the typical notion of moving from "abstract to specific"; only it may mean sequencing interactions and not necessarily level of detail (information). In other words, progressive disclosure is not just about displaying abstract then specific information, but rather about 'ramping up' the user from simple to more complex actions.
In its most formal definition, progressive disclosure means "to move complex and less frequently used options out of the main user interface and into secondary screens".
Examples
An example of progressive disclosure is the print dialog where you can initially choose how many copies to print, the printer to use and whether you want to print the full document or only certain pages. On the secondary (advanced options) screen one can then modify the full set of options.
In its purest format, progressive disclosure is about offering a good teaser. A good teaser can include the following:
Progressive disclosure says: "Make more information available within reach, but don't overwhelm the user with all the features and possibilities".
Related examples
An example for Staged Disclosure is an online news article that is spread across four screens (with a Next Page link at the bottom). This use of progressive disclosure serves advertising objectives (showing banners on each page) and not the user's task.
Another example would be a site that explains a product by making the user click through 4-5 pages of overview/benefits information before revealing the price of the product. The idea here is that if the user reads the product information, they will accept the price more easily. The problem with that approach is that it does not accommodate free-form exploration, a typical behavior on the web.
History
Progressive disclosure is a concept that has been around since at least the early 1980s. The technique caught the attention of user interface specialists with Jack Carroll's lab work at IBM (1983), where he found that hiding advanced functionality early on led to an increased success of its use later on. The approach dubbed "training wheels" is one of the few references validating the technique. Carroll and Rosson (1997) pointed out that no empirical evidence exists regarding the effectiveness of progressive disclosure and that the training wheels approach only studied a "single computer application (word processor) and a single interface style (menu based control)". While independent usability studies and consultancy research (including our own) has shown that appropriate usage of the technique is valuable, more empirical research is clearly required.
The software vs. web design environment
Historically, progressive disclosure is a concept that came from the software usability experience. It is clearly easier to apply to software than it is on websites. In software (including in web applications), the interaction is between dialogues and 'fixed state' interactions. On websites, interactions are chaotic, randomized and dynamic because hypertext is a non-linear media.
In the software world the audience is predictable and targeted, making learning styles more predictable. On a website, it's anybody's guess who might be using the site. The website visitor might be a particle physicist, a teen or a grandparent. Learning styles, comfort levels and expectations differ greatly. This is perhaps why you hear a lot of references to progressive disclosure in conversations and interviews, but rarely any ideas about how to apply it effectively.
Usability guru Jakob Nielsen mentions progressive disclosure regularly. Nielsen has stated:
"Good usability includes ideas like progressive disclosure where you show a small number of features to the less experienced user to lower the hurdle of getting started and yet have a larger number of features available for the expert to call up".
"Progressive disclosure is the best tool so far: show people the basics first, and once they understand that, allow them to get to the expert features. But don't show everything all at once or you will only confuse people and they will waste endless time messing with features that they don't need yet".
Effective use on the web
In true progressive disclosure, one would attempt to trigger a Snowball effect. This is the goal of progressive disclosure from a marketing standpoint.
Progressive disclosure on the web is when one only shows information that is relevant to the task the user wants to focus on, on any given page. Google pioneered this strategy with context-sensitive text ads.
Progressive disclosure is an interaction design technique that emerges from the insights gained during Task Analysis (user observation of tasks). Observing users in the field, allows one to understand their workflow outside of specific technologies. This insight provides the necessary data required to prioritize and sequence content and functionality.
Progressive disclosure can be validated by conducting task analysis (behavioral observation) with a user base. Observing users in their native problem solving environment provides data about how they interact with the information.