Study: iPhone owners make more errors during text entry
Posted by Dennis Sellers 
Nov 14, 2007 at 6:57am
User Centric, a Chicago-based usability consultancy, finished a third and final study examining the user experience of Apple’s iPhone. Previously, User Centric found that overall design and usability of the iPhone was good, but the iPhone’s touch keyboard was a weak point for many users.
The current study examines specific interactions with the iPhone touch keyboard and compares the texting experiences of iPhone owners and non-owners across devices. The study involved data from 60 participants who were asked to enter specific text messages and complete several mobile device tasks. Twenty of these participants were iPhone owners who owned their phones for at least one month.
Twenty more participants were owners of traditional hard-key QWERTY phones and another twenty were owners of numeric phones who used the “multi-tap” method of text entry. Participants were brought in for 75 minute one-on-one usability sessions with a moderator. Each participant entered six fixed-length text messages on their own phone. Non-iPhone owners also did six messages each on the iPhone and a phone of the “opposite” type.
The opposite phone for numeric phone owners was a Blackberry and for hard-key QWERTY phone owners it was a numeric Samsung E300 phone. Some participants did additional tasks, including a contact search and add contacts, as time allowed. This study used a mixed factorial design to compare the performance of the different types of phone owners while creating text messages on different types of phones (iPhone, hard-key QWERTY, and numeric phones).
User Centric defined performance in terms of time to complete tasks and number of errors made per text message. iPhone owners entered six text messages on their own phone. They also typed two pangrams—a sentence that includes every letter in the English language at least once—and one corpus—a set of characters that represents the exact letter frequencies of the English language. These tasks were included to ensure that participants experienced the various phone keyboards in a thorough manner, according to User Centric.
iPhone owners also completed tasks involving text correction, contacts, and visual voicemail Non-iPhone owners entered a total of 18 text messages—six each on their own phone (hard-key QWERTY or numeric phone), the iPhone, and the “opposite” phone (numeric test phone for QWERTY phone owners, hard-key QWERTY test phone for numeric owners). These participants also entered two pangrams and one corpus on their own phone and completed the contact list tasks if time was remaining. The order of phones and text messages were counterbalanced across participants to prevent ordering effects.
The text messages contained 104-106 characters, including spaces. Half of the messages contained 8-9 instances of capitalization and punctuation while the other half had none. Messages were never seen more than once by a participant. The pangram tasks contained 66-67 characters and the corpus consisted of 112 characters.
At the end of the session, all participants rated each phone and ranked them in order of ease of use for text messaging. When compared to hard-key QWERTY phone owners using their personal phones, iPhone owners’ rate of text entry on the iPhone was equally rapid. However, iPhone owners made more errors during text entry and also left significantly more errors in the completed messages. While iPhone owners made an average of 5.6 errors/message on their own phone, hard-key QWERTY owners made an average of 2.1 errors/message on their own phone, according to user Centric.
iPhone owners also left an average of 2.6 errors/completed message created on the iPhone compared to an average of 0.8 errors/completed message left by hard-key QWERTY phone owners on their own phone. When comparing the performance of iPhone owners and novices (non-iPhone owners), there was no significant difference between the number of errors made. iPhone owners were faster than non-iPhone owners.
“Despite the correction features available on the iPhone, this data suggests that people who have owned it for a month are still making about the same number of errors as the day they got it,” says Gavin Lew, managing director of User Centric. What’s more, when iPhone owners were asked to perform a text correction task during their sessions, 21 percent of iPhone owners weren’t aware of the magnifying glass correction feature although they had owned their iPhone for one month.
Participants who did know about the feature clearly loved it, and participants who were new to it indicated that it would be useful in the future, notes User Centric. Participants who had previously not used either a hard-key QWERTY phone or an iPhone were significantly faster at entering text messages on the hard-key QWERTY test phone than on the iPhone. These participants also made significantly fewer errors on the hard-key QWERTY than on the iPhone. Numeric phone owners made an average of 5.4 errors/message on the iPhone, 1.2 errors/message on the QWERTY test phone, and 1.4 errors/message on their own phone.
“Not only was their performance better,” says Jen Allen, user experience specialist for User Centric, “their rankings and ratings of the phones indicated that they preferred a hard-key QWERTY phone for texting.” Participants rated the hard-key QWERTY phone highest out of all three phones for ease-of- text messaging.
The hard-key QWERTY phone was also most frequently ranked first out of the three phones by the numeric and QWERTY users. Overall, the hard-key QWERTY phone was ranked first in text messaging by 85 percent of users. iPhone was ranked second by 60 percent of these users. None of the hard-key QWERTY phone owners ranked the iPhone first for text messaging and only three numeric phone owners ranked the iPhone first.
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Dennis Sellers
Dennis has been a newspaper editor/reporter (seven years) and teacher (seven years). He has over 4,000 magazine, newspaper and online articles to his credit. He has also covered the Mac and tech industries for over a decade for such online publications as MacCentral, MacMinute and now MacsimumNews.
