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A Study of the Effect of Thumb Sizes on Mobile Phone Texting Satisfaction

Vimala Balakrishnan and Paul, H.P. Yeow

Journal of Usability Studies, Volume 3, Issue 3, May 2008, pp. 118-128

Article Contents


The following sections present the subjects, thumb measurements, interview questionnaires, and interviews.


Text messaging is popular among young adults (Ling, 2001; Reid and Reid, 2004). Therefore, researchers recruited 110 adults between 17 to 25 years old (mean = 21.5 years, SD = 1.64) for the study. There were an equal number of males and females (55 for each gender). The subjects were Malaysians comprised of the three major ethnicities (Malays, Chinese, and Indians). The majority of the subjects (84/110) were students from a local university with diverse origins (representing different states in Malaysia). The rest of the subjects were recruited from public places such as local malls and libraries. All the subjects were familiar with SMS, with an average of 3.8 years of experience and SD = 1.19. All the subjects composed messages single-handedly using their thumb. For text entry, 80.9% (89/110) of the subjects used multitap, 11.8% (13/110) used both multitap and predictive interchangeably, and 7.3% (8/110) used predictive. The subjects responded to the interview questions based on their own mobile phones; therefore, the data collected captured the user's real feelings towards their own mobile phones. Table 1 shows the mobile phones used by the subjects in the study, the dimensions (range given based on the minimum and maximum width of the mobile phone), and also the weight of the phones (range between the lightest and heaviest mobile phone). The dimensions and the weight of the mobile phones reflect the current trend towards mobile phone miniaturization (the heaviest phone is merely 114g). All the mobile phones had a 4 x 3 keypad layout. The following is a list of some of the models used in the study:

Table 1. Mobile phone characteristics
Brand Ownership Dimension (mm)
(length x width x thickness)
Weight (gram)
Nokia 73 102 x 42.6 x 19.4 - 113 x 48 x 16 76-114
Samsung 14 80 x 40 x 22 - 111 x 45 x 17 72-85
Motorola 10 106 x 44 x 16 - 110 x 48 x 15 82-108
Sony Ericsson 9 102 x 43 x 17 - 101 x 48 x 19.5 84-93
Siemens 2 105 x 45 x 16 86
Alcatel 2 98 x 42 x 20 - 98 x 45 x 20 77-80

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