Small pocket computers offer great potential in workplaces where mobility is needed to collect data or access reference information while carrying out tasks such as maintenance or customer support. This paper reports on three studies examining the hypothesis that data entry by older workers is easier when the pocket computer has a physical keyboard, albeit a small one, rather than a touch-screen keyboard. Using a counter-balanced, within-subjects design the accuracy and speed with which adults over 55 years of age could make or modify short text entries was measured for both kinds of pocket computer. The keyboard computer was the Hewlett Packard 360LX (HP), but the touch-screen computers varied across studies (experiment 1: Apple Newton and PalmPilot; experiment 2: Philips Nino; experiment 3: Casio E10). All studies showed significant decrements in accuracy and speed when entering text via the touch-screen. Across studies, most participants preferred using the HP's small physical keyboard. Even after additional practice with the touch screen (experiments 2 and 3) many entries still contained errors. Experiment 3 showed that younger people were faster but not more accurate than older people at using the touch-screen keyboard. It is concluded that satisfactory text entry on palm-size computers awaits improvements to the touch-screen keyboard or alternative input methods such as handwriting or voice. Interface developments that assist older people typically benefit younger users too.

Two styles of pocket computer memory aid were compared as support for people who had sustained non-progressive, closed-head brain injury. A purpose-designed interface provided a diary with auditory alarms, a notebook and links between diary entries and specific notepages. One computer had a physical keyboard, the other did not. Twelve adult volunteers were loaned each computer for 2 months, with a 1 month gap between, in counterbalanced order. It was found that all participants could use the memory aids, and most (83%) found them useful. Little customizing was needed, but amount of use varied widely. Predictors of usage included use of other reminding systems before joining the project, and speed in calculator addition which may reflect working memory. High users preferred the computer with a physical keyboard; low users made more entries with the palm-size computer. These data highlight the need to distinguish ability to use from willingness to use.

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