Summary: 
Websites that let users customize the UI have the same measured usability as regular sites. Sites for customizing products, however, score substantially worse due to complex workflow.

Web-based customization is not new. As far back as the mid-1990s, people have touted customization as both the Web's destiny and the panacea to all business ills. After filtering out the hype, it's clear that Web-based customization can, in fact, be utilized to benefit both businesses and users…if implemented properly.

Customization's usefulness is obvious for many applications. Still, there are countless tales of companies investing heavily in customization only to find that users rarely — if ever — customize. There are also numerous studies that tout users' desire for customization, but (as we know) whatusers say is often at odds with what they actually do.

Ultimately, for customization to succeed, you must have a business need for it and identify realistic hard and soft benefits to offset the expense of implementing it correctly.

Customization vs. Personalization

Today, designs are often adapted to individual users, so that different people see different screens both in applications and on websites. There are two main ways to individualize the user experience, depending on who initiates the adaptation:

• Customization happens when the user tells the computer what he or she prefers to see. Examples include:
  • Changing a news site to display the user's hometown weather forecast upon future visits to the homepage.
  • Changing an automobile vendor's site to display a particular car model with specific color and feature options, along with the customized car's list price. Most auto sites now feature such configurators.
• Personalization happens when the computer modifies its behavior to suit its predictions about the current user's interests. Examples include:
  • An intranet portal employs role-based personalization to show management-related features only to users who are registered as managers in the HR database.
  • An e-commerce site displays a list of the user's last five orders to make reordering the same products easy.

1. Interface customization: Functionality that lets users customize their online experience by adapting the user interface to suit their preferences.
2. Product customization: Functionality, such as a configurator, that facilitates customization of offline products, including custom-manufactured products.

User Research

Interface Customization Sites

• iGoogle
• My Yahoo!
• Pageflakes

Product Customization Sites

• Custom Ink (custom t-shirts and other wearables)
• Action Envelope (custom envelopes)
• [me] & goji (custom cereal)
• Tiny Prints (custom invitations and announcements)

• Add a to-do list to your page
• Take a gadget off the page
• Add a feature that posts daily pictures of cats
• Assume that your business is moving and you need to print 500 announcements on a budget of $600

Business Benefits of Customization

Increased Traffic and Loyalty

In 2008, for example, iGoogle reportedly accounted for 20% of visits to Google's home page. As well, users who take the time to create their own custom Google or Yahoo! homepages are more likely to engage with site offerings such as Web-based e-mail and search.

Reduce Operating Costs

Cast a Wider Net

Usability Challenges on Customization Sites

In our post-task surveys, users generally reported feeling more lost and less in control on the customization websites, as the following (averaged) ratings indicate:

Having users feel less in control on customization sites is particularly unfortunate, given that the goal of customization is to cater more precisely to each user's needs. Current customization user experiences have a tendency to get in the way, rather than empower users and make them feel appreciated.

The complexities of customization impact both task success and perception of the site.

For interface customization, the main problems relate to discoverability, findability, and comprehension — that is, getting to the customization in the first place, and then finding and understanding the available options. To reward first-time users with an early success experience, sites should better explain features and provide fast-tracked workflows. In our study, for example, iGoogle's promise to create a simplified personal homepage "in under 30 seconds" was successful and encouraged users to start experimenting with the service.

For product customization, poor findability caused even more problems: it was responsible for45% of the many task failures on these sites. Overly complex workflows also caused many problems. Users frequently missed steps or misunderstood what was required to successfully design their own products. For example, one site asked users to specify font sizes in units that made no sense to the average person, resulting in a frustrating trial-and-error with different numbers. This particular problem was exacerbated by the unfortunate choice of a default size that was too small for almost all users.

The Importance of Good Defaults

It's too easy to resolve a design debate by simply offering all the possible options as preference settings and letting users decide the interface for themselves. Often, it's better for users if the design team decides on a single good, coherent user experience. Customization options should be reserved for those features that offer substantial user benefits, thereby compensating users for the time spent on customizing the UI rather than on accomplishing their tasks.

In any case, some users won't customize no matter how easy and rewarding you make the customization interface. It's therefore imperative to retain a good default design for non-customizing users.

Customization: Effective When Implemented Correctly

Customization is complicated, both technologically and design-wise. To get a user from blank slate to fully customized interface or product takes exceptional design skill. It also requires cooperation among multiple groups to assemble, organize, and architect a usable customization path. Customization isn't something you can throw together in a couple weeks, and businesses who approach it in that manner are risking their reputation and revenues.