Sunday, November 25, 2007

iPhone Users Make More Text Errors

Empirical results on iPhone usability ...

"Sold on usability, the iPhone may not be suitable for heavy text use is the conclusion of the third usability study by User Centric.

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.

... Texting Performance Compared
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). We 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. 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.
Equally Rapid but iPhone Owners Made More Errors
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, p < .01. 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.

Interestingly, when comparing the performance of iPhone owners and novices (non-iPhone owners), there was no significant difference between the number of errors made, p = .21. iPhone owners were faster than non-iPhone owners, of course.

“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.

Furthermore, when iPhone owners were asked to perform a text correction task during their sessions, 21% of iPhone owners were not 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."    (Continued via 160 Characters)    [Usability Resources]

iPhone Fingers - Usability, User Interface Design

iPhone Fingers


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