The iPad is selling like hot cakes. Already, Apple has sold more than 1m of the tablet devices.

But how does the iPad stack up in terms of usability? According to a
study conducted by Jakob Nielsen and his firm, Nielsen Norman Group,
there’s room for improvement.

To test the iPad’s usability, Nielsen Norman Group recruited seven testers to use it with a variety of popular apps and websites. All seven had at least three months’ worth of experience using the iPhone, but only one had experience with the iPad. That’s a limitation worth noting, but it also means that this study might provide a good level of insight into the new experience new iPad users are likely to have.

What Nielsen Norman Group discovered is a “triple threat” of iPad disadvantages that “causes significant user confusion“:

  • Low discoverability. In short, users are given no “perceived affordances” that indicate how different elements on the screen will react when they’re touched. This is problematic, obviously, because without these perceived affordances, users are unlikely to know what they’re supposed to do. Nielsen observes that the price users pay for the iPad’s “etched-screen” “beauty” is that they “don’t know where they can click.
  • Low memorability. Exacerbating the problem of low discoverability is the fact that iPad apps and websites behave differently. One example of this: touching a picture could produce five different results depending on the app or website. Because of this inconsistency, iPad users can’t transfer their skills from one app or website to another.
  • Accidental activation. Low discoverability and low memorability above contribute to unexpected results when a screen element is accidentally activated.

Interestingly, initial criticism of the iPad was that it simply looked like an enlarged iPhone. And based on the testing conducted by Nielsen Norman Group, it appears that it’s not just the device itself that has been scaled up, but the interface as well.

Unfortunately, Nielsen notes that the “iPad user interface shouldn’t be a scaled-up iPhone UI.” The iPad’s size and physical characteristics make it a much more ideal device than the iPhone to browse the web with. Whereas Nielsen’s past iPhone usability studies revealed that iPhone users prefer the app experience to the web experience, Apple is billing the iPad as “the best way to experience the web.

That Apple is marketing the iPad as a web browsing device makes sense. Given that the iPad sort of sits in a no-man’s land market between smartphones and netbooks/laptops, one would think that if the iPad is going to realize its full potential, consumers would need to embrace it as one.

The question is whether the usability issues that surfaced in this study will hinder the iPad’s adoption over the long haul. It will certainly be interesting to see if and how Apple, app developers and web designers address some of these issues.

Photo credit: cogdogblog via Flickr.